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SpaceX Hyperloop Pod Competition

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Re: SpaceX Hyperloop Pod Competition

#91

Post by martinald »

DuskStar wrote: post #82
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…

To be fair, Birmingham London is 125 miles, while Los Angeles San Francisco is 380 miles. A better comparison would be Edinburgh London, at 410 miles or so. At those distances, required capacity probably drops off.

Well, there's between one and two trains per hour between London and Edinburgh, each holding about 600 people. So that's more just on train capacity, and there's up to 53 flights a day between London and Edinburgh. So that's another 6000ish seats per day.

Just doesn't add up.

Re: SpaceX Hyperloop Pod Competition

#92

Post by netfire »

mixmastamyk wrote: post #77
netfire wrote: post #67

Earlier quoted context omitted.

Would a Hyperloop system work well in a system with frequent stops, where you wouldn't be able to get up to full-speed because you needed to stop and the stops could disrupt other express traffic. Would you really be gaining that much over other traditional rail transportation options? It seems like the strength of the Hyperloop is extremely fast travel over long distances. Personally, I think having a line between L…

I think it would, however I didn't realize until now how small the tubes and cars are, might make a metro-type system challenging. Or, it could be widened for metro usage, like the disneyland monorail.

Yeah, I wondered if some sort of on-ramp/off-ramp or multi-lane system might work, but given the distance it would take to get up to full-speed (or decrease speed to stop), that could greatly increase the cost of construction, especially if there are a lot of stations.

For the Hyperloop to make any sense in a shorter distance metro setting, you'd probably want to have no stops between where you start and your destination. (So you might go directly from Anaheim to Santa Monica, for example) With smaller cars/trains, this may be possible (since you might be able to fill trains quickly enough to not make people wait too long), but potentially very expensive to build enough lanes to manage that amount of traffic with greatly varying speeds efficiently.

Without that sort of system, however, I think the additional stops would delay you so much that the gain over a traditional metro train would be small and not worth the extra expense of building it.

Re: SpaceX Hyperloop Pod Competition

#94

Post by tallerholler »

Animats wrote: post #88

The original Hyperloop system was supposed to be powered by linear induction motors spaced along the track. The pod doesn't have propulsion capability, except maybe an emergency system. So the pod/track interface is pretty much set by the propulsion system. For trains, linear induction motors have usually been paired with magnetic levitation, as in the Transrapid system. But they don't have to be. Many roller coaster…

as an aside, holy crap that website is terrible!

Re: SpaceX Hyperloop Pod Competition

#95

Post by abduhl »

msandford wrote: post #72
abduhl wrote: post #66

Earlier quoted context omitted.

How is the issue of a horizontal slip different for a tunnel versus for an above ground structure? Neither piece of infrastructure can be economically designed to withstand a seismic movement if the structure crosses the fault where the offset occurs. Why does the possibility of an offset result in a tunnel being an "emphatic no" while still allowing for this pylon idea?

Because steel is very ductile and tough, where as concrete is very strong, but brittle. Make a tunnel in the ground with concrete and if the ground moves, your tunnel moves too, along with it. Unless your tunnel is stronger than the ground. Which it isn't. Or if it is, it's a 10ft diameter tunnel with 40 foot thick walls. Which is SEVERELY uneconomic. Make it out of steel and put it in the air, and things get a lot d…

If the pylons are every 100 feet and the joint offset is 20 feet between pylons then that implies a shear strain of .20. This is LARGE for a shear strain. Assuming a shear modulus of 11500 ksi then a shear strain of .2 results in a shear stress of 2300 ksi which is well beyond the ultimate strength of any steel that I've ever worked with.

Now your argument that the tube will just break free of the pylons seems like it has merit; however, the question of "why do we have all these pylons every 100 ft if we only need them every XXX ft?" should immediately spring to mind. The answer obviously lies with the rigidity of the tube between support points.

In order to get into the realm of the possibility for the steel being able to take a 20 ft offset you're talking about putting supports once a mile, at most.

Again, neither the pylon idea nor the tunnel idea have a feasible/economic engineering solution for displacement along a fault if it occurs along alignment.

Re: SpaceX Hyperloop Pod Competition

#96

Post by krschultz »

toomuchtodo wrote: post #34
krschultz wrote: post #29

Earlier quoted context omitted.

You're off by an order of magnitude on the cost of a TBM.

"The machine is a remarkable and unique piece of equipment. Purpose-built for Crossrail by German firm Herrenknecht – one of a handful of TBM manufacturers in the world – it cost around £10m ($15m), weighs close to 1,000 tonnes, has an external diameter of 7.1 metres (23ft) and from cutting-face-to-end stretches 150m (500ft)." http://www.bbc.com/future/story/20150602-crossrail-the-monst...

https://pedestrianobservations.wordpress.com/2012/04/20/quic...

$250 million for a water tunnel that goes 3km. It's simpler than a hyper loop tunnel.

Also I'm not sure Crossrail is a good counter example. That's a 30 billion dollar project to go 73 miles. Saying the TBM cost $20 million is like quoting the cost of a truck without including the price of the driver or diesel fuel.

Re: SpaceX Hyperloop Pod Competition

#97

Post by vidarh »

CodeSheikh wrote: post #68

"Neither SpaceX nor Elon Musk is affiliated with any Hyperloop companies" Yet it is hosted on spacex.com. I love the project but I hate the legalities here. What does that mean? If something bad happens during operation then these aforementioned entities cant be held responsible.

It means what it says. Various people have formed companies to try to commercialise the Hyperloop concept. SpaceX and Elon Musk are not affiliated with them.

SpaceX and Elon Musk are behind this competition.

Re: SpaceX Hyperloop Pod Competition

#98

Post by btilly »

abduhl wrote: post #90
btilly wrote: post #70

Earlier quoted context omitted.

The pylons are built with an internal structure allowing them to move horizontally both ways, and vertically. The tube itself can remain stationary in the air. We do not have a cost effective way to allow the tube to remain stationary if it is attached to the ground and the ground moves. And avoiding buckling and sudden bends kind of matters when you're traveling at mach 1. Search for "earthquake" in http://www.space…

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 already linked to. It includes graphs showing numerical simulations of how their design is supposed to respond to earthquakes. If you have further questions, you can start with that, then download the designs that they and others have produced and do your own work.

I am not an engineer. However I do know that engineers have done exactly what I suggested and come to the conclusion that his design is feasible.

Re: SpaceX Hyperloop Pod Competition

#99

Post by jcchin41 »

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

Re: SpaceX Hyperloop Pod Competition

#100

Post by abc_lisper »

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?

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