I don't believe that an experimental tube is going to be somehow magically cheaper and easier to route and build than train tracks.
Do you really think the special interests that are making HSR so difficult and expensive would say, "Oh, do whatever you like with your tube."?
These are extremely important issues that advocates seem to be glossing over. Putting the guideway on pylons doesn't magically eliminate land issues, you will still have to deal with visual impacts, along with any number of anticipated and unanticipated problems.
Musk should do what the Germans did with the TR0x series of maglev vehicles, build a 10-20 mile test section someplace and demonstrate that is analysis is sound.
(perhaps more in the future--why wouldn't California design with this goal [350 km/h] in mind?)
There are a variety of reasons, but one important reason I have to deal with is that the speed of shear waves through soil is only on the order of a couple of hundred miles per hour. When a train exceeds the shear wave speed, ground-borne vibration waves "build up" in a manner similar to the shock wave created in air when a plane exceeds the speed of sound, causing a ground-borne vibration equivalent of a "sonic boom" that can cause problems for wayside structures. I believe the French have started to experience this with some of their higher-speed TGV experiments and we don't have a good way to handle this yet.
> one important reason I have to deal with is that the speed of shear waves through soil is only on the order of a couple of hundred miles per hour.
Perhaps a stupid question, but the shock wave forms because the trains is moving continuously over the ground? So if you put the entire thing on stilts, there would be one wave formed at t0, x0 when the train reaches pylon 0 and the next wave would be at t1, x1 etc. So the interference pattern for the waves would look vastly different. ( This holds of course only for point like trains... )
Yes, rather than a line-source, you have multiple incoherent point sources, but those point sources are being excited along a line at a rate faster than the shear wave speed. So yes, it somewhat different, but also similar.
A test segment would go a long way to determining if/how much of a problem this might be in a hyperloop system.
> When a train exceeds the shear wave speed, ground-borne vibration waves "build up" in a manner similar to the shock wave created in air when a plane exceeds the speed of sound...
Putting the railway or tubes on pylons would give you an opportunity to dampen or otherwise transform those vibrations wouldn't they?
Putting the railway or tubes on pylons would give you an opportunity to dampen or otherwise transform those vibrations wouldn't they?
Maybe, maybe not. Guideway supports (pylons) are typically founded into the bedrock which does reduce vibration somewhat, but the vertical motion of the pylon moving against the soil will still generate shear waves.
This is why a demonstration project would be useful.
I recall reading that the pylons had vertical and horizontal dampers to protect against earthquakes (among other minor natural changes), so wouldn't those dampers be able to cancel out the shear waves?
No. Well, I suppose you could design an active vibration system to (almost) completely cancel the vertical vibration motion, but know you're talking about a powered system in each pylon of incredible complexity.
Passive resilient systems could help with higher frequency vibration (above say 100 Hz or so, depending on the forces and weights involved), but for lower frequency vibration (especially below 20 Hz), the resilient elements would have to be so compliant that even a gentle breeze would create very high vibrations in the guideway itself, which would be incompatible with the speeds of the cars inside.
You could make the pylons so massive that the forces from the vehicles couldn't move it, but again you're talking about higher construction and material costs, as well as visual impacts.
Vibration from trains is proportional to the unsprung weight of the vehicle (basically the axle, wheels and traction motors) rather than the vibration of the whole vehicle (which is isolated by the primary and secondary train suspensions). For a heavy rail transit vehicle (NYC transit, MBTA Red Line, CTA vehicle, etc), you're talking about 2,700 kg. I don't have numbers handy for HSR trainsets.
The plan uses an air bearing partly because an air bearing is exceptionally stiff. It's not like a hovercraft, with all that ability to squoosh up and down. So the unsprung weight might be the weight of the entire vehicle.
edit: though, mind you, the whole capsule also has mechanical suspension
Wow. I'm an Elon Musk fan too but this is a bit much. He didn't give anything to the world. He is a businessman-he gets paid very handsomely to do the things he does.
At very least, it is in society's best interest to socially reward people working on solving big problems instead of doing lucrative things that just exploit people.
True innovators carry all of humanity on their backs, and give massively to all of humanity, present and future.
The fact that they get some monetary compensation doesn't entitle you to not be grateful and to not recognize their heroism.
It does not entitle you to imply, as you have, that they deserve the same level of praise as any person who is paid for any work whatsoever.
You are, by implication, equating Elon Musk to the teenager flipping burgers, or any other menial laboror.
That is moral treason.
Without innovators, we would all be dying in pestilence-ridden Stone Age villages. In my opinion, those who claim that innovators do not deserve the highest of possible praise _deserve_ that fate.
Elon Musk is probably at least millions of times more productive than the average human.
If you were to calculate the sum of gains and losses between Elon Musk and humanity, it would balance out that Elon Musk is overwhelmingly the creditor, and humanity is overwhelmingly the debtor.
As with the great-grandparent of this comment, your comment is a massive moral equivocation.
I think tesla motors releasing an affordable car would benefit the world a lot more than the hyperloop. But it's nice that he is presenting the idea so the world can do their own analysis and even implement it before he has the chance.
>>I think tesla motors releasing an affordable car would benefit the world a lot more than the hyperloop.
Specifically, an affordable Tesla car could benefit the entire world, whereas the Hyperloop would (at least initially) only benefit people living in LA and SF.
They both benefit the world. Fact is, there is no modernized 3-Liter-Lupo, and I've heard no rumors that there ever will be (?). Until there is, Tesla will be the one who demonstrates what is possible.
Really specifically, an affordable Tesla would (at least initially) benefit only those who were able to buy an affordable Tesla given the still significant cost and Tesla production constraints.
They both have the potential to be hugely beneficial to the entire world. Although in Tesla's case it's more of a certainty... fortunately we can have both :-)
The pod is basically flying. Although its weight of course is still ultimately borne by the pythons, perhaps it's mushed out and dampened in a way that reduces the ground-boom effect? But it sounds like one of the (many) bugs that must be worked out. spaceX wasn't all smooth sailing.
Do you really think the special interests that are making HSR so difficult and expensive would say, "Oh, do whatever you like with your tube."?
These are extremely important issues that advocates seem to be glossing over. Putting the guideway on pylons doesn't magically eliminate land issues, you will still have to deal with visual impacts, along with any number of anticipated and unanticipated problems.
Musk should do what the Germans did with the TR0x series of maglev vehicles, build a 10-20 mile test section someplace and demonstrate that is analysis is sound.
(perhaps more in the future--why wouldn't California design with this goal [350 km/h] in mind?)
There are a variety of reasons, but one important reason I have to deal with is that the speed of shear waves through soil is only on the order of a couple of hundred miles per hour. When a train exceeds the shear wave speed, ground-borne vibration waves "build up" in a manner similar to the shock wave created in air when a plane exceeds the speed of sound, causing a ground-borne vibration equivalent of a "sonic boom" that can cause problems for wayside structures. I believe the French have started to experience this with some of their higher-speed TGV experiments and we don't have a good way to handle this yet.