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SpaceX Hyperloop Pod Competition

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Re: SpaceX Hyperloop Pod Competition

#101

Post by bsdetector »

jcchin41 wrote: post #99

For those interested in getting a better handle on the vehicle thermodynamics, see[1]. Feel free to play around with the open-source python model here[2] [1] https://mdao.grc.nasa.gov/publications/AIAA-2015-1587.pdf [2] https://github.com/OpenMDAO-Plugins/Hyperloop [3] http://www.popsci.com/hyped-up-startups-race-hyperloop-life

For those of us who aren't aeronautical engineers... if you just covered a normal expressway with a half tube, wouldn't the air start moving along with the vehicles and greatly decrease the drag at high speeds, making higher speeds more economical? Or at what point does the vacuum and ratio of vehicle to tube size make hyperloop work out, but a simple enclosed highway doesn't?

Re: SpaceX Hyperloop Pod Competition

#102

Post by abduhl »

btilly wrote: post #98
abduhl wrote: post #90

Earlier quoted context omitted.

I'm sorry but no - this does not answer the question. Expansion joints and "lateral dampers" do not make the problem of a joint offset go away. In order to resist a horizontal or vertical offset of 20+ feet with the tube "remaining stationary" then the pylon must be built to allow an extra 40+ feet to account for this movement. How, exactly, does the pylon not suffer the same design flaw as the tunnel under the use c…

Where do you get your 40+ feet figure from? If each side can move the tunnel 10 feet relative to itself without breaking, you should theoretically be able to handle up to a 20 foot slip between plates. One side bends one away, the other the other way. The pylons move 20 feet relative to each other, and only 10 feet relative to the tube. That said, my information is based on the blueprint that Elon published and I alr…

The 40 foot figure assumes that the direction of movement is unknown and that one pylon remains fixed. I suppose you could just have each pylon capable of handling 20 feet of three dimensional movement but I doubt the economics work out in favor of that option rather than choosing towers rationally.

That said, your answer is an appeal to authority. Just because a feasibility study says it is feasible does not actually make it feasible. I skimmed the document you linked and nothing in it pertains to large ground movements that would occur due to fault offset - it is all with relation to ground shaking rather than fault slip. Further, it is common knowledge, in fact, that underground structures generally perform better under ground shaking as compared to above ground structures except when the structure crosses the fault which experiences the offset. That is, tunnels work better than pylons except at the point where the large offset occurs.

I understand that you may not be an engineer. I am an engineer, with my area of expertise being in geo-structural interaction, and I am telling you that your statement about a tunnel not being feasible because of earthquakes is NOT correct. There are plenty of other reasons why a tunnel makes no sense for this job, but seismic vulnerability is not a good one. Whether his design is feasible or not is a moot point.

Re: SpaceX Hyperloop Pod Competition

#103

Post by dimlyaware »

michaelbarton wrote: post #63

This immediately reminded me of the early days of steam when, very similarly, at Rainhill a one mile test track of railway was constructed and people were invited to compete their different locomotives. The winner was Stevenson's rocket which amazed the large crowd by travelling at a heady top speed of 30mph. An "also ran" was the amusing cycloped, the only non-steam entry, a horse on top of a treadmill walking the c…

That fact really made me laugh when I looked into it. Thank you for the cycloped fact.

Re: SpaceX Hyperloop Pod Competition

#104

Post by TeMPOraL »

impish19 wrote: post #69
TeMPOraL wrote: post #23

Earlier quoted context omitted.

They could use what I will call a rocket-estate crash coupling: 1. "Accidentally" crash a rocket near some properties there (far enough not to do any actual damage). 2. Wait for said property prices to crash.

You can't be serious.

Can't I?

Re: SpaceX Hyperloop Pod Competition

#105

Post by btilly »

abduhl wrote: post #102
btilly wrote: post #98

Earlier quoted context omitted.

Where do you get your 40+ feet figure from? If each side can move the tunnel 10 feet relative to itself without breaking, you should theoretically be able to handle up to a 20 foot slip between plates. One side bends one away, the other the other way. The pylons move 20 feet relative to each other, and only 10 feet relative to the tube. That said, my information is based on the blueprint that Elon published and I alr…

The 40 foot figure assumes that the direction of movement is unknown and that one pylon remains fixed. I suppose you could just have each pylon capable of handling 20 feet of three dimensional movement but I doubt the economics work out in favor of that option rather than choosing towers rationally. That said, your answer is an appeal to authority. Just because a feasibility study says it is feasible does not actuall…

Slip is defined by relative displacement, not absolute displacement. See http://earthquake.usgs.gov/learn/glossary/?termID=174 for verification. So in a 20 foot slip, neither side actually moved 20 feet.

Secondly it is very important that the tube remain still while the pylons move relative to it. Don't forget that we have objects moving down that tube at close to the speed of sound. It doesn't take a large local kink to be a fatal problem for people inside. You really don't want that tube to move. Enough so that keeping the tube still that it is an explicit design consideration to keep it still while the pylons expand and contract for thermal reasons.

Thirdly I well know that earthquakes are generally less of problems underground than on the surface. But trading an easy problem in most places with an impossible problem at fault boundaries is hardly an improvement. That is why I have only focused on the potentially impossible problem.

Fourth, your response was just as much an appeal to authority as mine. But my appeal to authority was an appeal to authorities whose credentials are independently verifiable, whose conclusions have been put up for public comment, and which other authorities have independently questioned, criticized, and mostly verified. Your authority is based on an anonymous claim of expertise made on the internet, in a thread where you made a basic mistake about how earthquakes are measured, with no actual analysis backing it up.

Which authority is more believable?

Re: SpaceX Hyperloop Pod Competition

#106

Post by abduhl »

btilly wrote: post #105
abduhl wrote: post #102

Earlier quoted context omitted.

The 40 foot figure assumes that the direction of movement is unknown and that one pylon remains fixed. I suppose you could just have each pylon capable of handling 20 feet of three dimensional movement but I doubt the economics work out in favor of that option rather than choosing towers rationally. That said, your answer is an appeal to authority. Just because a feasibility study says it is feasible does not actuall…

Slip is defined by relative displacement, not absolute displacement. See http://earthquake.usgs.gov/learn/glossary/?termID=174 for verification. So in a 20 foot slip, neither side actually moved 20 feet. Secondly it is very important that the tube remain still while the pylons move relative to it. Don't forget that we have objects moving down that tube at close to the speed of sound. It doesn't take a large local kin…

You are standing on one side of the fault and you move 10 ft north. Your pylon is standing on the other side of the fault and it moves 10 ft south. The total relative movement is 20 ft. If the assumption is that all of the relative movement is accommodated at one pylon then the pylon must be able to move 20 ft in a single direction. If the direction of the fault offset is unknown then the pylon must be able to move 20 ft in all directions for a total distance of 40 ft. We appear to be talking past each other here.

My response is not an appeal to authority - I'm not saying "it's true because I'm an engineer". I walk you through the entire logical process, so you're free to agree or disagree with any of my arguments.

This conversation clearly isn't going anywhere so I will just reiterate my point and leave it at that: an above-grade structure will perform no better than a below-grade structure if the fault deformation occurs at the location where the fault crosses the alignment. This "potentially impossible problem" is a problem for both surface and underground structures and cannot be designed around from the structural side for the magnitude of displacement that can potentially occur in CA and, in the end, it is just a risk that has to be accepted or designed around from the systems standpoint. This is alluded to in your own linked documents and noted by the the statement:

"It is also likely that in the event of a severe earthquake, Hyperloop capsules would be remotely commanded to actuate their mechanical emergency braking systems."

I guess to answer your question: I'd probably believe me.

Have a nice day.

Re: SpaceX Hyperloop Pod Competition

#107

Post by melloc »

abc_lisper wrote: post #100
michaelbarton wrote: post #63

This immediately reminded me of the early days of steam when, very similarly, at Rainhill a one mile test track of railway was constructed and people were invited to compete their different locomotives. The winner was Stevenson's rocket which amazed the large crowd by travelling at a heady top speed of 30mph. An "also ran" was the amusing cycloped, the only non-steam entry, a horse on top of a treadmill walking the c…

Hoping you were not old enough to know this first hand ;) This is fascinating? Where did you come across this info?

There's a Wikipedia article on this, it seems:

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

Re: SpaceX Hyperloop Pod Competition

#108

Post by harperlee »

guynamedloren wrote: post #58

Any engineers or mechanically inclined folks around LA interested in assembling a team? Let's chat. About me: full stack software engineer with a degree in Systems Engineering from University of Illinois Urbana-Champaign. I work on classic cars and build shit with my hands when I'm not coding. I'm into efficiency, and I loooove the idea of building a better, faster cheaper CA high-speed railway.

So now I'm very curious: can anyone comment on what's the biggest collaboration of this sort to have come out of Hacker News?

Re: SpaceX Hyperloop Pod Competition

#109

Post by Gustomaximus »

martinald wrote: post #75

The projections of capacity seem way too low. It says it can do 840passengers/hour. In the UK each 11 car train on the West Coast Mainline can take about 600 passengers seated + maybe slightly over 100 more standing. So around 700. We have 3 trains per hour between London and Birmingham, which adds up to a rough capacity of 2200 per hour. This doesn't even take into account the multitude of slower trains that go betw…

Rather than 2 parallel hyperloops would it be more efficient to make passing points? Orgainse timings so pods pull off at a platform and then car traveling in the opposite direction or overtaking can go past.

Re: SpaceX Hyperloop Pod Competition

#110

Post by Andrenid »

cloudwalking wrote: post #55
imglorp wrote: post #52

I wonder what they will do about claustrophobia? > The capsule itself would need to be small—4.43ft (1.35m) wide and only 3.61ft (1.10m) high. No standing room No windows, pod inside a metal tube, seats reclined with minimal head room. There's no rational reason to panic in that position, but many people will not be comfortable. Video displays might help, but only to a point.

VR goggles.

VR goggles displaying a view of outside, maybe recorded from a plane that flew the same path then synced to your location to simulate your actual trip.

The feeling to your body would then match the view too.

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