Imagine if half of these commenters were around when the Wright brothers were pioneering aviation?
Hyperloop One Becomes ‘Virgin Hyperloop One’
111–120 of 517 posts
Re: Hyperloop One Becomes ‘Virgin Hyperloop One’
#112The engineering has never been a problem, vacuum-tube trains are an idea that's been around for centuries. [1] Removing friction and air resistance is a simple physics problem, and there are already operational maglev [2] trains so putting them in a low-pressure tunnel is not a major revolution. The real issue is the viability of such a transport because of the cost, complexity, and construction effort involved. We (…
"We can barely build a high-speed rail line effectively...' There is no high-speed rail line in the United States. The nearest thing to high-speed rail is the Acela Express, which hits 240kph on 40km of track. But this is weaksauce by modern standards.
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Re: Hyperloop One Becomes ‘Virgin Hyperloop One’
#113Earlier quoted context omitted.
This point is clearly addressed in the paper: The ends of the tube can slide 300 meters next to the station, and the tube is not firmly attached to the pylons but can move to accommodate the expansion.
No. The paper gets this badly wrong. It looks only at the incremental thermal expansion between pylons, and neglects the fact that in a sealed tube the thermal expansion will be cumulative. "These would absorb the small length changes between pylons due to thermal changes, as well as long form subtle height changes." [emphasis added] The cumulative expansion is dealt with in a single sentence: "A telescoping tube, si…
How about you also copy the sentence that lies just between those two?
"As land slowly settles to a new position over time, the damper neutral position can be adjusted accordingly."
And if that doesn't work, the tube can have some kind of rails or just to roll over wheels on top of the pylons. (my own thoughts as non expert)
Rocket engineers with advanced simulation tools[0] have been working on this for 5 months before releasing the paper. Do you really think they somehow missed this obvious issue?
[0] https://www.youtube.com/watch?v=vYA0f6R5KAI
Edit: Further in the paper it says: "The tube will be supported by pillars which constrain the tube in the vertical direction but allow longitudinal slip for thermal expansion as well as dampened lateral slip to reduce the risk posed by earthquakes."
So pretty much what I've said. The other quoted sentence refers to placement of pylons themselves.
Re: Hyperloop One Becomes ‘Virgin Hyperloop One’
#114Something I wrote a while ago.... w/ back of the napkin calculations....... Why I wouldn’t invest a money into Hyperloop - Stabilizing a single fault line risk pylon is more than $250K. - How many million are needed for vacuum pumps to evacuate 100+ million cubic feet of of pipe to 100 Pa? - Hot air discharge needs to go somewhere. For every 1 bar pressure, you need ~200 to ~400 cubic meters of volume which is larger…
Assuming your are correct and Branson knows it because he hired good engineering advisers. Why would Branson get involved ?
- It is a cool project he wants to be part of and he is willing to pay to see. (I would probably do that)
- The benefit is not to reach the goal but all the technology that will be invented trying to reach the goal.
Re: Hyperloop One Becomes ‘Virgin Hyperloop One’
#115Earlier quoted context omitted.
The CERN LHC tube is a 27km circle of vacuum and near-zero temperature, and they don't seem to have a problem with that (granted, they had some but it's solved now). Frankly, yes, there may be issues, but I'm confident that the Human race will be able to overcome those.
What about building a high speed train? Proven technology, works in a lot of countries. LA to SF in 2 hours. Is it really that bad?
It'll be more like 3 hours, and it will end up costing around $100 billion. It would be dramatically cheaper and faster to subsidize free plane tickets between LA and SF for the next 50 years.
HSR works well in places with high density and competent infrastructure construction strategies. California has neither.
Re: Hyperloop One Becomes ‘Virgin Hyperloop One’
#116Earlier quoted context omitted.
When Musk first said that an LA SF Hyperloop could be built for 1/8th the cost of the equivalent HSR, I chuckled and then waited for the punchline, which still hasn’t arrived. It’s a cool idea and I do want to see more prototypes and feasibility studies, but people need to get off the hype train (no pun intended) and be realistic about the cost.
Okay, we'll bookmark this for the future. Amtrak estimated a HSR/"bullet train" from D.C. to Boston would cost ~$151 billion. Since LA to SF will only be two stops, and we can assume Amtrak estimated at least 4 (Philly and NYC) let's bring the number down closer to $100 billion to make it even. Do we think the Hyperloop costs are more or less than that? 1/8 of a theoretical $100b is $12.5b -- is $12.5billion for Hype…
You cannot compare D.C to Boston with SF to LAX. The east coast has much denser population so that you need more tunnels. LAX to SF HSR would not cost $151bn. Start and end are expensive but the part in the middle is "relatively" cheap.
Re: Hyperloop One Becomes ‘Virgin Hyperloop One’
#117The engineering has never been a problem, vacuum-tube trains are an idea that's been around for centuries. [1] Removing friction and air resistance is a simple physics problem, and there are already operational maglev [2] trains so putting them in a low-pressure tunnel is not a major revolution. The real issue is the viability of such a transport because of the cost, complexity, and construction effort involved. We (…
"The engineering has never been a problem, vacuum-tube trains are an idea that's been around for centuries. [1] Removing friction and air resistance is a simple physics problem" "simple" Getting to Mars is a simple delta-v engineering problem. Nuclear fusion is a simple magnetic field engineering problem. Self driving cars are a simple programming problem. Don't ever change, Hacker News.
Ok, we did get rovers to Mars decades ago so I'm sure you know what I mean here, but you seem to be making my point that it's not worth it.
Simple isn't the same as easy, but an evacuated train tunnel with air or magnetic tracks does not require new science. The physics are well understood and simple. The hard part is evolving the tech to be reliable and cheap so that people will use it and pay for it - but that doesn't seem to be within economic reach, and that's before factoring in construction and upkeep.
Re: Hyperloop One Becomes ‘Virgin Hyperloop One’
#118Earlier quoted context omitted.
I dont know if this an elephant in the room. I'm guessing engineers have thought about this and just not discussed it publicly. They have some pretty smart guys. Also to nitpick, from "the ends of a viable hyperloop track will have to move hundreds of meters" - this doesn't have to be true. There can be absorption points along the track. Overlaps. Or maybe they tunnel the entire way where its cooler. Or wrap the tunn…
Wouldn't they just put accordion joints on the junction at every pylon? It's not like the tube is going to be built as one gigantic piece. It has to be assembled from parts.
The vacuum is the problem. With HSR you also have small gaps in the system to allow for expansion but nothing there requires a perfect surface.
Re: Hyperloop One Becomes ‘Virgin Hyperloop One’
#119The viability of Hyperloop One should not be the focus in the context of this article. That's not what this is about at all. It's that Hyperloop One needed Richard Branson on board because Elon Musk is creating his own competitor now. This is an incredibly smart move to ensure the survivability of the business from a publicity perspective. Branson has a history of doing things that people thought impossible or just a…
Branson's missing a d from his almost nominatively-determining name — the guy's got a talent for self publicity over challenging the incumbency, which for the most part he hasn't since launching Virgin Airlines and Megastores, which were both back in the 80s.
"Branson's missing a d from his almost nominatively-determining name"
Wat?
Edit: This has been a fun puzzle. I read the Wikipedia article for "Nominative determinism" and I've been swapping the letter "d" into various positions of his first and last name trying to figure it out. No luck yet!
Re: Hyperloop One Becomes ‘Virgin Hyperloop One’
#120Earlier quoted context omitted.
> There can be absorption points along the track Sure, but these have to hold a vacuum. No one has figured out a way to do that.
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.