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

Hyperloop Freight is a Joke

pedestrianobservations.wordpress.com

Post reply on HN
Print view View original

111–120 of 177 posts

Re: Hyperloop Freight is a Joke

#111

Post by jheriko »

D_Alex wrote: post #82
LordHumungous wrote: post #62

Of course the hyperloop is a joke. Elon Musk has zero experience or training in transportation infrastructure, but we are supposed to have faith in some idea he farted out in a white paper, why? Because he has skillfully cultivated his image as a "genius", and we bought it? The hyperloop was nothing more than a (savvy) PR move to cement his image as a "visionary". That it actually got funded only goes to show what gu…

Elon Musk had zero experience building cars, yet he made Tesla happen. Perhaps a high intellect and a good general purpose engineering training can accomplish more than you think. You, on the other hand, are overwhelmed by the challenge of maintaining vacuum in a tube that spans a mere 17 miles. At the very least, you should restrain yourself from using language like "...some idea he farted out...".

be careful, tesla is not successful as a car company yet, and its not in good shape to become one either.

one day it might be, and more generally i do hope that we see more progress in the electric car world... but for now tesla only turns a profit as a car company coupled with government incentives. even then, outside of the US (and inside actually) their market share is tiny or zero with very little growth. saying that it doesn't even exist is a very good approximation to reality... if you ignore tech focused news articles and the like at least.

i wouldn't call that a success just yet... as much as we may admire the mission.

Re: Hyperloop Freight is a Joke

#112

Post by ubernostrum »

nothrabannosir wrote: post #108
LordHumungous wrote: post #62

Of course the hyperloop is a joke. Elon Musk has zero experience or training in transportation infrastructure, but we are supposed to have faith in some idea he farted out in a white paper, why? Because he has skillfully cultivated his image as a "genius", and we bought it? The hyperloop was nothing more than a (savvy) PR move to cement his image as a "visionary". That it actually got funded only goes to show what gu…

If I take your first paragraph and replace Hyperloop with Space X, it sounds like something one could have said back when that started. Yet here we are. I'm no expert either, but that sounds rather hollow..

SpaceX's success is largely due to not having to perform all the hard R&D of rocketry up-front. They got that done for them, for free, by major governments in the 50s and 60s. So now SpaceX can simply build off that, making evolutionary rather than revolutionary changes to the technology and turning it into a profitable business.

But Hyperloop is unexplored territory. There isn't billions/trillions of fundamental R&D already done and given away for free by somebody else. I suspect that's going to have an impact.

Re: Hyperloop Freight is a Joke

#113

Post by schiffern »

problems wrote: post #12
Russell91 wrote: post #2

I always come to these hyperloop criticisms expecting to find some sort of fatal flaw in the physics of energy efficient supersonic travel. But to my surprise, they instead tend to be pessimists saying things like, "You'll never get past my friends: the regulators, the government bureaucrats, and especially the lawyers!. We will drive up your costs and make you look foolish". First, no one said that designing this th…

The best legitimate criticisms I've seen are here: https://m.youtube.com/watch?v=RNFesa01llk Basically expansion and contraction as well as just plain vulnerability of running a vacuum make it extremely difficult to do practically. The phrase he uses, "all the problems of space travel except in a gun barrel" is a pretty accurate description of the issue. Any loss of vacuum will almost guarantee loss of life. No reali…

Ahh yes, the infamous Thunderf00t "debunking" video. Never have so many Hyperloop myths been created by a single piece of content! I've debunked-the-debunking a half dozen times myself, and it shows no signs of slowing down.

The big problem with his air cannon theory is, pipes are not lossless! Friction and viscous interactions between the entering air and the tube wall will slow down that "shock front" to a highway speed wind in only a couple km. So unless it's so close that the pod can't stop in time (and actually derails at the breach), there should be no loss of life.

As far as thermal expansion, that can be solved with sliding interfaces every few hundred meters. The Hyperloop has switched to mag-lev designs for levitation, so the ultra smooth interior is no longer necessary. There will be some air leakage at the joint of course, but this can easily made up by the pumping stations installed at intervals along the track.

The pressure in the Hyperloop was specifically chosen so that simple mechanical vacuum pumps can be used -- no turbomolecular or cryopumps needed. The Hyperloop runs at 1/1000th of an atmosphere. True "vacuum trains" use vacuums at about 1/1,000,000th of an atmosphere, meaning the pumping is about 1000 times harder (not because the pressure difference is meaningfully different, but because you only get 1/1000th as much air per "stroke" or "cycle").

The Large Hadron Collider uses a harder vacuum still (about 1/1,000,000,000,000 of an atmosphere, and yes that's a trillionth of an atmosphere), which is why LordHumungous's experience mentioned earlier isn't terribly applicable. The LHC is doing something a lot harder than the Hyperloop.

Re: Hyperloop Freight is a Joke

#114

Post by wbl »

Someone wrote: post #86
LordHumungous wrote: post #62

Of course the hyperloop is a joke. Elon Musk has zero experience or training in transportation infrastructure, but we are supposed to have faith in some idea he farted out in a white paper, why? Because he has skillfully cultivated his image as a "genius", and we bought it? The hyperloop was nothing more than a (savvy) PR move to cement his image as a "visionary". That it actually got funded only goes to show what gu…

The LHC has lower pressure than Hyperloop is supposed to have (1E-7 pascal, reading http://www.lhc-closer.es/taking_a_closer_look_at_lhc/0.high_... versus 100 pascal, reading https://en.m.wikipedia.org/wiki/Hyperloop#Theory_and_operati... ) Still quite challenging, but not in the same league, even considering that hyperloop requires way longer tunnels.

The forces aren't much different, even if the allowable leakage is higher and the pumping easier.

Re: Hyperloop Freight is a Joke

#115

Post by D_Alex »

LordHumungous wrote: post #83
Omniusaspirer wrote: post #68

Earlier quoted context omitted.

Would you be able to tell us about some of the problems the LHC faced? Hyperloop aside, this is an interesting subject.

The tolerances on each part must be very tight. If there is a single flaw in one part, the whole vacuum fails. The challenges become exponentially greater as you scale up the diameter of the pipe, since the force on the pipe is proportional to the square of the radius. The LHC had a 50mm diameter pipe, the hyperloop proposes an 8+ foot diameter. You do the math.

When you said that you worked on the LHC for several years - what was your role, and how were you involved with the vacuum system? Because your answers show a serious lack of understanding.

First, part tolerances are not a particularly important issue with engineering of high vacuum systems (sealing is effected by compression of gaskets, usually soft stainless steel gaskets for UHV systems).

Secondly, the difficulties in maintaining a large UHV system is usually related to "outgassing", from multiple surfaces and/or material imperfections, and are rarely due to "a single flaw in one part".

Thirdly, you are using the word "exponentially" wrong, even in the context of your flawed claim which is addressed below.

Finally: "the force on the pipe" is not, in a meaningful sense, proportional to the square of the radius. The forces in the pipe wall are proportional directly to the radius (formula is stress=pressure*radius/thickness), if it was otherwise pipe thickness would grow as the square of diameter and large pressurised pipes would be physically impossible.

Happy to do the math for you when you need it, best to leave it to the experts.

Re: Hyperloop Freight is a Joke

#116

Post by yellowapple »

"This is actually worse for freight than for passengers, which is why the speed limits on curves are lower for freight trains than for passenger trains"

I'm 91% sure that this is less to do with freight specifically and more to do with the amount of weight involved and how it's distributed in each car. Then again, I'm no expert on freight trains.

Re: Hyperloop Freight is a Joke

#117

Post by syngrog66 »

D_Alex wrote: post #82
LordHumungous wrote: post #62

Of course the hyperloop is a joke. Elon Musk has zero experience or training in transportation infrastructure, but we are supposed to have faith in some idea he farted out in a white paper, why? Because he has skillfully cultivated his image as a "genius", and we bought it? The hyperloop was nothing more than a (savvy) PR move to cement his image as a "visionary". That it actually got funded only goes to show what gu…

Elon Musk had zero experience building cars, yet he made Tesla happen. Perhaps a high intellect and a good general purpose engineering training can accomplish more than you think. You, on the other hand, are overwhelmed by the challenge of maintaining vacuum in a tube that spans a mere 17 miles. At the very least, you should restrain yourself from using language like "...some idea he farted out...".

also he started a successful, innovative new rocket company

Re: Hyperloop Freight is a Joke

#118

Post by crdoconnor »

jheriko wrote: post #111
D_Alex wrote: post #82

Earlier quoted context omitted.

Elon Musk had zero experience building cars, yet he made Tesla happen. Perhaps a high intellect and a good general purpose engineering training can accomplish more than you think. You, on the other hand, are overwhelmed by the challenge of maintaining vacuum in a tube that spans a mere 17 miles. At the very least, you should restrain yourself from using language like "...some idea he farted out...".

be careful, tesla is not successful as a car company yet, and its not in good shape to become one either. one day it might be, and more generally i do hope that we see more progress in the electric car world... but for now tesla only turns a profit as a car company coupled with government incentives. even then, outside of the US (and inside actually) their market share is tiny or zero with very little growth. saying…

>but for now tesla only turns a profit as a car company coupled with government incentives.

Subsidies and protective tariffs are the norm in the auto market.

It would put any car company that didn't get them at a significant disadvantage.

Re: Hyperloop Freight is a Joke

#119

Post by Retric »

ubernostrum wrote: post #112
nothrabannosir wrote: post #108

Earlier quoted context omitted.

If I take your first paragraph and replace Hyperloop with Space X, it sounds like something one could have said back when that started. Yet here we are. I'm no expert either, but that sounds rather hollow..

SpaceX's success is largely due to not having to perform all the hard R&D of rocketry up-front. They got that done for them, for free, by major governments in the 50s and 60s. So now SpaceX can simply build off that, making evolutionary rather than revolutionary changes to the technology and turning it into a profitable business. But Hyperloop is unexplored territory. There isn't billions/trillions of fundamental R&D…

Hyperloop can leverage trillion in highly relevant fundamental R&D also. For example aircraft already operate at low enough external pressure to quickly kill the passengers ex: concord was under 1/20th ATM. Yet, loss of cabin pressure is a very rare situation. There is a lot of proven technology to maintain low vacuum cheaply, as a first step to achieving high vacuum. Massively improved battery technology enables reasonably high energy density's which are very much necessary. etc.

Now, sure there is a lot of new tech that would be needed. But, less than you might think.

Re: Hyperloop Freight is a Joke

#120

Post by D_Alex »

robotresearcher wrote: post #104
D_Alex wrote: post #82

Earlier quoted context omitted.

Elon Musk had zero experience building cars, yet he made Tesla happen. Perhaps a high intellect and a good general purpose engineering training can accomplish more than you think. You, on the other hand, are overwhelmed by the challenge of maintaining vacuum in a tube that spans a mere 17 miles. At the very least, you should restrain yourself from using language like "...some idea he farted out...".

> You, on the other hand, are overwhelmed by the challenge of maintaining vacuum in a tube that spans a mere 17 miles. You say 'overwhelmed' but I'll just point out it is built and working, and at almost-perfect vacuum.

Yes... it clearly is a manageable issue. The opening comment writer was the one who was overwhelmed, and no surprise given his lack of understanding demonstrated in his answer elsewhere. I just hate it when people with such a lack of knowledge make rude, hateful remarks.
Post reply on HN