91–100 of 177 posts
Earlier quoted context omitted.
Where do you get all that helium?
I don't know, maybe from the 175 million cubic meters produced annually? For a 300km, two lane stretch you'd require around 7.5mln cubic meters - sure, that's a lot, but it's not an impossible amount.
Earlier quoted context omitted.
The tolerances on each part must be very tight. If there is a single flaw in one part, the whole vacuum fails. The challenges become exponentially greater as you scale up the diameter of the pipe, since the force on the pipe is proportional to the square of the radius. The LHC had a 50mm diameter pipe, the hyperloop proposes an 8+ foot diameter. You do the math.
The Hyperloop will operate at about 15 psi pressure differential maximum (i.e., one atmosphere). The Alaska Pipeline is certified to operate at 1,180 psi. It's not a problem, and minor leaks are not a problem, either. A leak that would stop a particle accelerator dead in its tracks will just make a hyperloop operate at slightly lower efficiency. Plus you can always just run the pump (any practical design will doubtle…
I always come to these hyperloop criticisms expecting to find some sort of fatal flaw in the physics of energy efficient supersonic travel. But to my surprise, they instead tend to be pessimists saying things like, "You'll never get past my friends: the regulators, the government bureaucrats, and especially the lawyers!. We will drive up your costs and make you look foolish". First, no one said that designing this th…
Pessimism seems to be the default for the HN hivemind. Would be cool if we all just encouraged everyone working on moonshots.
Positive thinking never solved anything.
I guess the 18,000 packages per hour that arrive at ANC by jet must also be a matter of "face"?
What does this even mean?
Edit for clarity: The FedEx terminal at Ted Stevens Anchorage International Airport can handle 13,400 packages per hour. The UPS terminal there handles about 5,000 packages per hour. Virtually all of these packages arrive from Asia on jets traveling hundreds of miles per hour (as opposed to the alternative, container ships, which are cheaper, but much slower).
That's because Anchorage is the major airport that's closest to being on a great circle route between North America and Asia. Most of the packages clear customs in Anchorage, and are then fed into the FedEx and UPS systems for further distribution throughout North America.
Clearly there is a very large market for moving cargo at 500 miles per hour. Frankly, I have a hard time believing that an "expert in logistics" would make such a statement.
Earlier quoted context omitted.
Elon Musk had zero experience building cars, yet he made Tesla happen. Perhaps a high intellect and a good general purpose engineering training can accomplish more than you think. You, on the other hand, are overwhelmed by the challenge of maintaining vacuum in a tube that spans a mere 17 miles. At the very least, you should restrain yourself from using language like "...some idea he farted out...".
Given that the Hyperloop is failing spectacularly, "a high intellect and a good general purpose engineering training" seem empirically to not accomplish quite as much as you think they do -- although, in fairness to high intellect and good general purpose engineering training, there was never any real reason to think that they'd be able to accomplish magic.
2) Which Hyperloop is failing? There are at least three groups, and as far as I know, they haven't even got close to testing the system, let alone know if it's a failure or not.
I'm skeptical of the whole concept, but declaring failure at this stage is no less silly than assuming it'll definitively work.
One thing the article misses is inflexibility. One of the big disadvantages of rail is that once the track is deployed it is very costly and difficult to upgrade it. One thing I'd want in any "futuristic" freight hauling method would be ease of scaling I don't think Hyperloop offers anything over rail in this regard once track is installed you are more or less stuck with the installed capacity forever. A computer ana…
The thousand-dollar-per-strawberry market cares a lot about latency, and not one jot about bulk handling capacity. Getting from Napa Valley to New York, New York in an hour without sitting in a box in the sun would be a big win.
Vactrains might work out. There's nothing wrong with maglev in an evacuated tube. A system where the thing runs on open track until it gets out of the city and can switch to a vacuum tube might work. Then you can get someplace useful. Most of the "hyperloop" proposals, including the MIT demo, are really maglev vactrains. If you're already a maglev, a tube doesn't add much. Japan's maglev has already reached 600 Km/h.…
Hypothetically, the vacuum tube gives you energy efficiency. Drag power is proportional to the cube of velocity, so drag energy losses over a fixed distance are proportional to the square. In an ideal world you're paying a fixed cost per unit time to pump the tube down then you shove as much stuff as you can through it at transsonic speed, catch it all with regenerative brakes at the other end, and pay an energy per…
Earlier quoted context omitted.
Reading through the criticisms the consensus is "sure, this can work if you allocate 10-100x more money than estimated." I'm not sure if it's truly innovative if it costs more, places considerable stress (up to 0.5g!) on the rider/cargo (what the author calls a "barf ride"). The analysis picks apart the touted benefits of additional speed when ultimately the capacity is lower and it takes longer to depart. In the cas…
I think the biggest point the article makes is the great deal of care that needs to be taken in packing loads to meet weight requirements and avoid movement of goods in transit. What makes sense for international air mail doesn't make sense for a four hour journey by truck, especially if that truck can take a container straight from the ship to the city depot without carefully repacking everything, or go door to door…
Earlier quoted context omitted.
I dunno... I'd feel much more comfortable if all humanities smartest technical people were trying to make the next whatsapp clone /s
Contrarily, I'd feel more comfortable if "idea guys" like Musk would leave the engineering to actual engineers.
Earlier quoted context omitted.
That demo is unrealistic. The entire end of the tube isn't going to open all at once. Instead, any realistic leak would be pretty small in comparison.
I don't understand why a tube section couldn't come away? What if a bomb went off, a truck hit a support beam, or an earthquake caused a section to topple over... I don't think it is unrealistic at all.