Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Hyperloop: Pipes of Fancy

economist.com

Post reply on HN
Print view View original

291–300 of 322 posts

Re: Hyperloop: Pipes of Fancy

#291

Post by ashtonkem »

_ph_ wrote: post #270
ashtonkem wrote: post #266

Earlier quoted context omitted.

“For higher capacities, special vehicles for those tunnels could be constructed”. Congratulations, you’ve rediscovered the subway. If Musk wants to make the argument that he’s found a way to drastically reduce subway construction cost, I’m all ears. But he should jump straight to that, rather than this ludicrous idea of zipping personal cars around under the streets; a proposal that doesn’t come anywhere close to the…

Yes, he claims to have found a way to drastically reduce construction consts. First of all, reducing the tunnel diameter, as the digging speed is constrained by volume. Second, he tries to improve the technology of tunnel boring machines. With the smaller tunnels, there is the requirement for smaller vehicles. You can't run standard trains through these tunnels. For now, he is using Teslas (quite obvious choice) to d…

> It is so funny how people critisizing Musk assume, he wouldn't understand so simple connections like seats per vehicle and transit density.

Well, he does keep showing renderings of public transit stations full of Teslas and not, you know, people. It's not really a big leap to say that he doesn't understand when he keeps marketing as if he doesn't understand.

Re: Hyperloop: Pipes of Fancy

#292

Post by johnwalkr »

captainbland wrote: post #257
johnwalkr wrote: post #246

Earlier quoted context omitted.

The tube would need egress points, interfaces to stations. I think the difficulty of building one tube between stations is like building a 100km long airplane fuselage. But any proposal is little more than "'just' build a tube!"

The difference between what an aircraft fuselage and what the hyperloop tube needs to do actually seem to be quite massive (caution, back of napkin understanding from somebody who is casually interested but by no means an engineer). The hyperloop is apparently to be pressurised at around 1/1000th of the pressure of the atmosphere (around 0.015psi). An airplane cabin is apparently pressurised to around 11-12 psi and a…

I like the spacecraft analogy! It’s hard to overstate how much more difficult it would be compared to “just building a tube”

Re: Hyperloop: Pipes of Fancy

#293

Post by liability »

grecy wrote: post #281
kwhitefoot wrote: post #255

Earlier quoted context omitted.

> lots of open land beside the existing road, Then you can just build a conventional 300kph high speed train and track. They are 'off the shelf' commodities these days. It will still be competitive with flying.

> It will still be competitive with flying. Flight time is 1 hr 20 mins. At 300kph it's going to take a high-speed train almost 3 hours.

Factor in time wasted at the airport when you show up early because the TSA is unreliable. I always give myself at least an hour extra and sometimes that's cutting it razor close.

And frankly not being subjected to the TSA is generally worth at least a few hours of my time. I'll sooner drive six hours than fly one because of those worthless assholes.

Re: Hyperloop: Pipes of Fancy

#294

Post by nytgop77 »

The_Double wrote: post #214
sudosysgen wrote: post #109

Earlier quoted context omitted.

What do you do when a terrorist shoots a hyperloop tube causing a pressure wave that will kill everyone inside?

What do you do when a terrorist places a derailing device [0] on a piece of rail track that will harm and potentially kill many people inside? [0]: https://en.wikipedia.org/wiki/Derail

Derailed train seems to injure most passangers, but kill only few of them [1] [2]. It would seem that hyperloop would be more similar to a plane - more deaths than injuries. Also damage to infrastructure, would be more than a few rails. (please educate me if I'm wrong)

[1]https://en.m.wikipedia.org/wiki/2017_Washington_train_derail... [2]https://en.m.wikipedia.org/wiki/List_of_rail_accidents_(2010...

Re: Hyperloop: Pipes of Fancy

#295

Post by liability »

The_Double wrote: post #214
sudosysgen wrote: post #109

Earlier quoted context omitted.

What do you do when a terrorist shoots a hyperloop tube causing a pressure wave that will kill everyone inside?

What do you do when a terrorist places a derailing device [0] on a piece of rail track that will harm and potentially kill many people inside? [0]: https://en.wikipedia.org/wiki/Derail

If you derailed a train, you'd lose what, tens of millions of dollars worth of locomotives, cars, and maybe a mile of track? When a hypertunnel explosively pressurizes, chances are you'd lose tens of billions of dollars of tube, plus anything that was anywhere in it.

Re: Hyperloop: Pipes of Fancy

#296

Post by nytgop77 »

sudosysgen wrote: post #123
yellow_postit wrote: post #120

Earlier quoted context omitted.

You avoid building it (above ground at least) in the first place

Even building it below ground doesn't work, they just have to punch a hole in the station while it is pressurized.

How much damage would a bullet hole actually do?

If the hole stays of fixed diameter, its throughput would be small compared to the volume of the tube, so pressure would increase gradually.

So, how feasible is it that hole would not increase? What hyperloop designs are there? 10 inch thick steel throughout whole length?

Re: Hyperloop: Pipes of Fancy

#297

Post by liability »

Ajedi32 wrote: post #288
sudosysgen wrote: post #122

Earlier quoted context omitted.

Yep, except that in order to match the capacity of the Montreal metro system you would need to have a car departing every 2 seconds, which is impossible.

One car every 2 seconds sounds totally plausible. In fact, that number actually seems pretty low to me. A single lane/tunnel should be able to handle automated cars traveling at a 2-second following distance no problem, so that just leaves loading/unloading as a potential bottleneck. How many on-ramps do you think it would take to reach a capacity of 0.5 cars/second? I'm really curious as to what sort of problems you…

How many amusement parks can load a ride car once every two seconds? Even continuously moving ski lifts aren't anywhere close to that and that's basically ideal conditions where the seat is delivered straight to your butt, and most users can reasonable be expected to be fit and coordinated. In the real world, people dawdle. You'd probably need dozens of loading lanes to reach .5/s, which means the stations are very large and expensive caverns.

Re: Hyperloop: Pipes of Fancy

#298

Post by sudosysgen »

Ajedi32 wrote: post #288
sudosysgen wrote: post #122

Earlier quoted context omitted.

Yep, except that in order to match the capacity of the Montreal metro system you would need to have a car departing every 2 seconds, which is impossible.

One car every 2 seconds sounds totally plausible. In fact, that number actually seems pretty low to me. A single lane/tunnel should be able to handle automated cars traveling at a 2-second following distance no problem, so that just leaves loading/unloading as a potential bottleneck. How many on-ramps do you think it would take to reach a capacity of 0.5 cars/second? I'm really curious as to what sort of problems you…

You need people to drive their cars safely into the intake with an average delay of two seconds, to match a very middling subway system running at a delay of 7 minutes instead of 2, assuming that every single car is filled to the brim. This is completely ridiculous. You won't be able to make people do anything with an average delay of 2 seconds, without any mistakes. The question isn't on-ramps, it's getting people to merge or arrive at the dispatch on average every two seconds without making any mistakes.

Re: Hyperloop: Pipes of Fancy

#299

Post by nytgop77 »

therealdrag0 wrote: post #278
heavenlyblue wrote: post #195

Earlier quoted context omitted.

Your assumption is only true if trying never has a negative downside.

I don’t see how that follows.

My take on the GP meaning: Failure diminishes trust from investors.

If you got 1 milliion from investors, and you blew it/wasted it/burned it. It will be harder to get the million for the 2nd idea.

Re: Hyperloop: Pipes of Fancy

#300

Post by grecy »

liability wrote: post #293
grecy wrote: post #281

Earlier quoted context omitted.

> It will still be competitive with flying. Flight time is 1 hr 20 mins. At 300kph it's going to take a high-speed train almost 3 hours.

Factor in time wasted at the airport when you show up early because the TSA is unreliable. I always give myself at least an hour extra and sometimes that's cutting it razor close. And frankly not being subjected to the TSA is generally worth at least a few hours of my time. I'll sooner drive six hours than fly one because of those worthless assholes.

Australia doesn't have the TSA...
Post reply on HN