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Hypnotized by Hyperloop

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Re: Hypnotized by Hyperloop

#181

Post by wolfram74 »

nickparker wrote: post #177
jonstewart wrote: post #133

Earlier quoted context omitted.

One feature of classical mechanics is that the world must abide by it. With transportation, the vehicle must start and stop at a speed of zero. The energy required to accelerate the vehicle to its top speed and then decelerate it to back to zero increases quadratically as the top speed increases. Another feature of classical mechanics is, of course, that Aristotelian concept of kenophobia, or horror vacui, or resinte…

The energy required only grows quadratically if you stay on one technology. Simultaneously switching from internal combustion to linear electric motors with efficient regen. braking and bumping the speed up 10x turns out to be a wash.

To clarify, you are stipulating that electric engines and regenerative breaking are ~100 times more efficient than a combustion engine? Because mv^2 means a 10 fold increase in speed is a 100 fold increase in kinetic energy.

Re: Hypnotized by Hyperloop

#182

Post by [deleted] »

nickparker wrote: post #177
jonstewart wrote: post #133

Earlier quoted context omitted.

One feature of classical mechanics is that the world must abide by it. With transportation, the vehicle must start and stop at a speed of zero. The energy required to accelerate the vehicle to its top speed and then decelerate it to back to zero increases quadratically as the top speed increases. Another feature of classical mechanics is, of course, that Aristotelian concept of kenophobia, or horror vacui, or resinte…

The energy required only grows quadratically if you stay on one technology. Simultaneously switching from internal combustion to linear electric motors with efficient regen. braking and bumping the speed up 10x turns out to be a wash.

[deleted]

Re: Hypnotized by Hyperloop

#183

Post by stcredzero »

dalbasal wrote: post #159
stcredzero wrote: post #143

Earlier quoted context omitted.

One feature of the transport market (from a mile high view) is that demand is almost infinite. It seems this is also true for cars and trucks. No matter how many roads we build, there is congestion. I think automated cars are going to show that one of the limiting factors to how much our society uses such transportation is the supply of piloting labor. Also to chime in: It's not literally infinite. It's just much hig…

I think for it (demand) is very high, but it's not really possible to say for sure without supplying a lot more, free piloting can give us. I think infrastructure will continue to be the limiting factor.

* I think infrastructure will continue to be the limiting factor.*

Autopilots with superhuman reflexes and "telepathic" sharing of sensor data/intelligence could be used to increase the carrying capacity of roads by almost an order of magnitude. Photos of roads indicate that we are only using 1/10th of them to carry cars, spatially speaking.

Re: Hypnotized by Hyperloop

#184

Post by kurthr »

eesmith wrote: post #141
kurthr wrote: post #126

Earlier quoted context omitted.

I thank you for bringing this up and the chance to read about this issue elsewhere, but no it isn't a problem. We have 2000km long gas pipelines. They dont worry about it (on the surface where temperatures actually change). Serpentines work... there are so many solutions that one could be accidentally introduced. I think we're discussing a bikeshed.

Gases don't care about g-forces going through an expansion loop/bend. We still haven't solved the thermal expansion problem for railroads. Hot weather can cause tracks to buckle. It can also cause roadways to buckle.

So you expect this to be above ground? I'd expect that it would be bored since (in states where mineral rights aren't held by the land owner) it's cheaper than above ground right of way. At boring depths (greater than 60ft or 20m) temperature change is less than 0.1c and thermal expansion ~10ppm. Serpentines 100km in diameter could easily be used with radial deflections of only 10cm. The g-load at 1080km/hr=300m/s with 100km radius is less than 1/10th of a g.

You should be designing with much larger margins than 10cm and 0.1g for anything carrying humans. Shock absorbers in the pod to deal with short range ripples (100um/100m) would be a much bigger issue. That's what I mean by accidental serpentine that makes the problem completely secondary.

If you've got calculations, then show them... otherwise please find a different bike shed.

Re: Hypnotized by Hyperloop

#185

Post by thatfrenchguy »

pas wrote: post #157
ComradeTaco wrote: post #138

Earlier quoted context omitted.

There is a functional limit for induced demand! But it effectively can't be reached in urban and suburban areas because cars scale really poorly. Cars don't scale well for three main reasons: (1) Cost. Building roads and highways inflicts both huge upfront capital costs and maintenance costs. A typical highway line has a throughput of 2,000 cars per hour. (2) Real Estate. Building the level of roads necessary to meet…

Only cost is important for tunnels, because there's still space sufficient for hundreds of layers of tunnels below cities.

Look at Paris, this is not true.

Re: Hypnotized by Hyperloop

#186

Post by thatfrenchguy »

pas wrote: post #157
ComradeTaco wrote: post #138

Earlier quoted context omitted.

There is a functional limit for induced demand! But it effectively can't be reached in urban and suburban areas because cars scale really poorly. Cars don't scale well for three main reasons: (1) Cost. Building roads and highways inflicts both huge upfront capital costs and maintenance costs. A typical highway line has a throughput of 2,000 cars per hour. (2) Real Estate. Building the level of roads necessary to meet…

Only cost is important for tunnels, because there's still space sufficient for hundreds of layers of tunnels below cities.

Look at Paris, this is not true.

Re: Hypnotized by Hyperloop

#187

Post by Turing_Machine »

jonstewart wrote: post #133
dalbasal wrote: post #18

One feature of the transport market (from a mile high view) is that demand is almost infinite. If you can get 40kms in 45 minutes, then you can live within 40 miles of work and commute in that time. If you could go 400kms, then that becomes your commuting radius. We've seen people spread this way as earlier mechanized transport was invented. IE, average commute times didn't go down because of faster transport, distan…

One feature of classical mechanics is that the world must abide by it. With transportation, the vehicle must start and stop at a speed of zero. The energy required to accelerate the vehicle to its top speed and then decelerate it to back to zero increases quadratically as the top speed increases. Another feature of classical mechanics is, of course, that Aristotelian concept of kenophobia, or horror vacui, or resinte…

> The energy required to accelerate the vehicle to its top speed and then decelerate it to back to zero increases quadratically as the top speed increases.

What? No. You can, in fact, recover a substantial portion of the energy used to accelerate the vehicle when you decelerate it (quite a lot of it, if it's running in a vacuum with minimal frictional losses). The track would act as a linear motor during acceleration, and a linear generator during deceleration.

> Of course we now know we can produce vacuums these days... but it's not easy to make one.

You don't need a vacuum anywhere near as hard as the Sandusky facility for a transportation system. That operates at 10e-6 torr, while the Hyperloop will operate at 100 Pascals (about 0.75 torr, or 75,000 times higher).

Re: Hypnotized by Hyperloop

#188

Post by chiefofgxbxl »

stcredzero wrote: post #143
dalbasal wrote: post #18

One feature of the transport market (from a mile high view) is that demand is almost infinite. If you can get 40kms in 45 minutes, then you can live within 40 miles of work and commute in that time. If you could go 400kms, then that becomes your commuting radius. We've seen people spread this way as earlier mechanized transport was invented. IE, average commute times didn't go down because of faster transport, distan…

One feature of the transport market (from a mile high view) is that demand is almost infinite. It seems this is also true for cars and trucks. No matter how many roads we build, there is congestion. I think automated cars are going to show that one of the limiting factors to how much our society uses such transportation is the supply of piloting labor. Also to chime in: It's not literally infinite. It's just much hig…

And self-driving cars may increase congestion yet.

Whatever speed gains self-driving cars may attain by reducing time spent at a (now deprecated) traffic light or at an intersection/yield sign, people may just make more trips because road conditions have temporarily improved, thus cancelling that benefit.

Say you decide not to drive to work but instead take the rail because you don't want to deal with the hassle of traffic. Maybe the rail has its downsides too, but they are acceptable to you. Now if self-driving cars makes highway congestion to work better, you may just be that person who switches from rail to car.

Re: Hypnotized by Hyperloop

#189

Post by Turing_Machine »

kome wrote: post #42

Hyperloop is such a bad idea on so many levels. Mass transportation is the future: trains, suburban trains and metros. Not cars or "mini metros for cars". Super fast trains are already there. Europe lives in the future compared to the USA.

"Europe lives in the future compared to the USA."

Europe is the size of a postage stamp compared to the USA (or even worse, Canada).

Oregon is larger than the UK. Texas is larger than France. Alaska is larger than all of Western Europe.

Re: Hypnotized by Hyperloop

#190

Post by dwaltrip »

njarboe wrote: post #13

Such a negative, do-nothing article. "taking every billionaire’s quirky visions at face value". Elon Musk is a bit different than every billionaire. Re-usable orbital class boosters and the Model S is what gives Elon the street cred others don't have. "so-called Boring Company" WTF? The New Yorker was always a purveyor of a certain type of elitism, but since the Trump election they have really upped the intensity. No…

Obviously, Musk is killing it with Tesla and SpaceX. There is no doubt about that. He will be remembered in the history books for this.

But is he really serious about this Boring company stuff? The whole thing sounds ludicrous. Even if he reduces cost 10x, they are still crazy expensive and have a lot sorts of strange complications. I don't get it.

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