Hyperloop One Becomes ‘Virgin Hyperloop One’ • Hacker News Board

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#361

Post by aswanson » Thu, Oct 12, 2017, 9:27 PM UTC

KGIII wrote: post #315

aswanson wrote: post #302

Earlier quoted context omitted.

Reminds me, Im just as guilty. Check out my insights on Amazon introducing the Kindle: https://news.ycombinator.com/item?id=81804

Yeah, we've all got comments from our past that we wish we'd not made. Our seemingly brilliant insights aren't so brilliant after all. Today's thread about Musk's "Hyperloop" is good fodder to bookmark and look back at in a decade. I have to wonder how many of the posters will admit they were wrong, should this reach fruition? I dug the link out for another person who replied. You may want to take a look? https://tec…

Thanks for that, belly laughing. One common thread of these "brilliant" dismissals, mine included, is that they undervalue how much people don't like going through technical hurdles with products and how much they will pay to avoid them and get on with what they want to do. Also, for ambitious goals like hyperloop, many assume technical challenges are insurmountable.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#362

Post by doingmything » Thu, Oct 12, 2017, 9:35 PM UTC

kbenson wrote: post #273

nradov wrote: post #226

Earlier quoted context omitted.

That's barely faster than driving, once you account for the time spent moving between your origin/destination and the train station as well as transferring luggage.

And taking the light rail north of SF to the ferry and then the Embarcadero in SF takes longer than driving when my brother commutes, but he still chooses that method. Perhaps there are factors other than time that go into his calculation. People would take HSR even if it took the same time as driving. They would likely take it if it took an extra 20%, as the time has more utility to them when used for a train ride.…

Agreed. Many people underestimate the aversion of a large swath of the population to driving. Driving basically monopolizes your time and focus and exposes you to accidents. I don’t know if I know anyone who would rather drive if they could get to their destination in the same relative time, unless they’d need a car on the other end.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#363

Post by goodcanadian » Thu, Oct 12, 2017, 9:41 PM UTC

lisper wrote: post #10

All of the Hyperloop development efforts are ignoring the elephant in the room: thermal expansion. If you do the math, the ends of a viable hyperloop track will have to move hundreds of meters [1]. No one has yet advanced even a viable idea for how to deal with that, let alone an actual design. Until that happens, the Hyperloop is vaporware. [1] It's a trivial calculation. The thermal expansion coefficient of steel i…

Many replies mention expansion joints. There are also other techniques that can be used: for example pre-stressing as is done with continuous weld rails:

https://en.wikipedia.org/wiki/Rail_stressing

Overall, it is not a particularly difficult engineering problem.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#364

Post by jgamman » Thu, Oct 12, 2017, 9:43 PM UTC

daemin wrote: post #165

Just as a thought experiment, could the promotion of these "hyperloop" projects be a clever political ploy to misdirect/divert attention and prevent a viable high speed rail network from being built? Elon's main business is electric cars and (one of) Branson's is airlines. So a reasonable competitor to both is fast and cheap(er) public transport along a major travel corridor in the USA. This means that by promoting t…

Transpower in nz used this argument to drastically cut its maintenance budget in the 90s using "distributed generation will strand the assets" type reasoning. Nz suffered the consequences. Who pays taxes and who booked imaginary accounting profits is left as an exercise for the reader. So yeah, it's not obviously wrong as a concern.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#365

Post by kbenson » Thu, Oct 12, 2017, 9:50 PM UTC

JumpCrisscross wrote: post #356

kbenson wrote: post #349

Earlier quoted context omitted.

I think what we have here is someone applying a known problem and solution space for one industry (rocketry) to another (civil engineering). A large vertical tube that needs to move quickly and under great stress may not allow for the same solutions that apply to a large horizontal tube that is relatively static. Fixing a large enough solar shield above a rocket hundreds of feet in the air which has to get out of the…

> I'm not sure how this problem was solved in rocketry is necessarily indicative of how hard it is to solve in other circumstances Very fair. The advantage a rocket has is you choose when it's rolled out. You don't have to design for the worst weather because you can always hide. You can't do that for a static structure. The Hyperloop is an attempt to marry the challenges of rocketry to the standards of civil enginee…

So, to make sure I understand the problem correctly, you expect thermals to develop under shaded portions that still cause heat, and that to affect the structure's top and bottom heat differential to a degree that it would still cause problems? Is this different than oil pipelines because of the low pressure and lack of a heat transferring medium to even the temperature of the tube? I'm trying to figure out how this would affect a proposed hyperloop system, when it seems sufficiently solved for other above ground pipeline systems.

I can see relative size, inside medium, building material differences, shading structures and acceptable tolerances all affecting the outcome one way or the other, but I'm not sure to what degree each one would affect the outcome, so I'm not sure if it's actually as hard as you make it sound or whether a solution is known and achievable.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#366

Post by twic » Thu, Oct 12, 2017, 10:09 PM UTC

Brakenshire wrote: post #249

mseebach wrote: post #223

Earlier quoted context omitted.

Meh. The imminency of "Major New Technology Just Around The Corner" has always been a favourite argument for the anti-progress crowd. EDIT to add: Before Hyperloop, it was Maglev. And frankly, a significantly better argument against HS2 is that it's an impossibly expensive boondoggle.

> a significantly better argument against HS2 is that it's an impossibly expensive boondoggle. Nah, it connects most of England's largest cities, and will be 2/3rds of the network which will connect all of the cities of the North of England into something approaching a single labour market. Liverpool, Leeds, Sheffield, Manchester, Birmingham will be all be within 30-50 minutes of each other, with London within an hou…

The main point of HS2 is that it will relieve congestion on the existing tracks, and allow more commuter services to run:

https://www.railengineer.uk/2014/01/03/the-capacity-benefits...

http://www.citymetric.com/transport/hs2-isnt-about-north-eng...

The idea that it will turn a load of separate cities into one big city is basically fantasy, as i understand it - this is about HS3, but the analysis is much the same:

http://www.citymetric.com/transport/crossrail-north-really-b...

And yes, i do get all my information from CityMetric, since you ask. It's basically Buzzfeed for transport policy, i love it.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#367

Post by nkoren » Thu, Oct 12, 2017, 10:10 PM UTC

dx034 wrote: post #120

nkoren wrote: post #66

Earlier quoted context omitted.

I am assured by those in a position to know that thermal expansion joints which hold a near-vacuum are an entirely solved and essentially trivial problem. I do have some concerns about whether they're a trivial problem within this context. An engineering solution which works in small numbers for PhDs in a lab isn't necessarily scalable to mass low-cost manufacturing, deployed in the field and irregularly serviced by…

And, more importantly, can be certified for real world use. Considering the speeds used, scrutiny will be extremely high. Even if you use it for freight at first, the track will be close to settlements and any accident could end up in a disaster. The behaviour of trains on tracks is very well understood (learning from accidents), the behaviour of a vacuum train tube is not.

This is a very fair point. There might be components that are routinely used in non-life-safety-critical applications, but this is no guarantee that they will pass certification scrutiny when they are in the critical path for thousands of lives every day.

I worked on an autonomous vehicle project here in the UK about 10 years ago (the Heathrow Pod). The certification process was absolutely intense. And this was for a system that was capped at 25mph; had we gone any faster than the regulatory burden would have become very significantly more onerous (below 25mph it wasn't necessary to test vehicles and infrastructure to destruction; above 25mph, it is).

In this domain, there's a huge difference between a cool engineering testbed, a private pilot project, and running actual service for the public. If Hyperloop is going to be doomed by anything, failure to appreciate this fact is probably at the top of the list.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#368

Post by JumpCrisscross » Thu, Oct 12, 2017, 10:17 PM UTC

kbenson wrote: post #365

JumpCrisscross wrote: post #356

Earlier quoted context omitted.

> I'm not sure how this problem was solved in rocketry is necessarily indicative of how hard it is to solve in other circumstances Very fair. The advantage a rocket has is you choose when it's rolled out. You don't have to design for the worst weather because you can always hide. You can't do that for a static structure. The Hyperloop is an attempt to marry the challenges of rocketry to the standards of civil enginee…

So, to make sure I understand the problem correctly, you expect thermals to develop under shaded portions that still cause heat, and that to affect the structure's top and bottom heat differential to a degree that it would still cause problems? Is this different than oil pipelines because of the low pressure and lack of a heat transferring medium to even the temperature of the tube? I'm trying to figure out how this…

> Is this different than oil pipelines because of the low pressure and lack of a heat transferring medium to even the temperature of the tube?

Most hydrocarbon pipelines run HTHP: high temperature, high pressure. This keeps their contents viscous. That, in turn, means heat emanates relatively uniformly from inside the pipe. For pipelines subjected to asymmetric expansion (e.g. when starting up or shutting down), they "walk".

"Walking behaviour occurs as the pipeline is heated, and expands asymmetrically, until the point when pipeline expansion is fully mobilised. Expansion is ‘fully mobilised’ when a virtual anchor forms near the centre of the pipeline. The virtual anchor is then stationary, while pipe to each side expands away from the anchor as the temperature continues to rise. Once expansion is fully mobilised, walking ceases for that cycle." [1] As long as it walks laterally, pipeline owners tend to be fine with it

The solution to walking is typically laissez faire (taking care to ensure the deformation occurs laterally, i.e. side to side, versus sticking a butt up into the water.) Needless to say, this isn't an option for the Hyperloop.

Granted, the contents of these pipes operate at 130º to 170º C. They're also narrower, resist a smaller pressure differential, face fewer such asymmetric events and don't face the stress of capsules periodically whizzing past inside them. Our tube won't displace by meters. Its displacement, moreover, won't be problematic on day one. But over time it will critically weaken known materials. Big, dynamically mechanically stressed, close to vacuum and above ground is hard.

[1] https://www.researchgate.net/profile/David_Bruton/publicatio...

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#369

Post by rrix2 » Thu, Oct 12, 2017, 10:21 PM UTC

ac29 wrote: post #338

mhermher wrote: post #282

Earlier quoted context omitted.

That must be new. That wasn't available as of like we years ago or so.

That rail route has ran continuously since 1971: https://en.wikipedia.org/wiki/Coast_Starlight . The transbay tube connecting Oakland to San Francisco via BART opened in 1974.

it's worth noting that coast starlight's once-a-day-each-way schedule sort of makes it limited as a commuter rail option.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#370

Post by monocasa » Thu, Oct 12, 2017, 10:24 PM UTC

icebraining wrote: post #350

monocasa wrote: post #233

Earlier quoted context omitted.

Yeah, Denver being chosen just convinced me that this whole thing is pump and dump cash grab. CDOT has this thing for "public/private partnerships" which are just thinly veiled schemes siphoning off taxpayer money. The whole US36 debacle proved to me that they aren't capable of negotiating a good deal on the part of the taxpayers.

What whole thing? The Denver partnership was made by Hyperloop One, which is just one of the companies trying to build it, and is not affiliated with Elon Musk.

Sure, 'the whole thing' being Hyperloop One in this case.