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Hyperloop Freight is a Joke

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Re: Hyperloop Freight is a Joke

#171

Post by ant6n »

Animats wrote: post #73

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.…

Conventional rail has hit 575km/h in tests (https://en.wikipedia.org/wiki/TGV_world_speed_record). What advantage does Maglev give? It mainly seems super expensive and incompatible with existing networks.

Note the main way in which the JR Maglev will allow adding speed is by building a very straight line for a lot of money, which could benefit conventional rail just as well.

Re: Hyperloop Freight is a Joke

#172

Post by na85 »

Manabu-eo wrote: post #170
na85 wrote: post #26

Earlier quoted context omitted.

Contrarily, I'd feel more comfortable if "idea guys" like Musk would leave the engineering to actual engineers.

Dozens of engineers from Tesla and SpaceX contributed in the Hyperloop whitepaper. Plus Elon considers himself an engineer, even though he has a degree in physics.

I consider myself a brain surgeon.

Re: Hyperloop Freight is a Joke

#173

Post by toomanybeersies »

Retric wrote: post #164
toomanybeersies wrote: post #134

Earlier quoted context omitted.

Aeroplanes are probably a more accurate approximation of what you'd feel. You get hardly any G force from banked highways, your speed is just too low. Now I don't really get plane sick, I will quite happily sit through a few barrel rolls (which is far more extreme than the hyperloop (although that would be fun)), but there's plenty of people who would get sick from a few 1.5 G banked turns. Elevators are different be…

High end cars can pull up to 1g lateral forces and many cars can pull up to 1g breaking on a good road surface. Relatively low top speed just means you don't accelerate very long. I have hit weightlessness over a hill at high speeds followed by 1.x g on the other side, so 0.5 g does not seem bad. Remember 1g * 1 second is only ~22mph.

For sure, my car is a pile of junk and can hit 1g braking.

The problem is when it's sustained. That's why people get sick on roller coasters and when doing aerobatics (extreme examples, I know).

Re: Hyperloop Freight is a Joke

#174

Post by brandmeyer »

mangeletti wrote: post #130
brandmeyer wrote: post #126

Earlier quoted context omitted.

Air has viscosity. Even for extremely smooth surfaces, you would expect the flow to be fully turbulent over such a distance.

What I mean is that the energy wouldn't be lost. The turbulence wouldn't result in a net loss of energy, except that which was lost as heat through the walls (a 1cm layer of vacuum would insulate against that). Am I thinking if this wrong?

Totally wrong. All of that turbulence goes into heat, which must be sunk through the walls (or something else), and is therefore lost. "Fully turbulent flow" is a reference to the transition away from (low-friction) laminar flow. Flow gets to be fully turbulent by experiencing high internal fluid friction due to its own viscosity. Air's viscosity is low relative to water, but it still isn't zero. 500 mph flow through a big long tube is extremely lossy.

Re: Hyperloop Freight is a Joke

#175

Post by mypalmike »

taneq wrote: post #135
mypalmike wrote: post #106

Earlier quoted context omitted.

What about one where you feel that, acting in various directions, at every curve, every speed transition, and every elevation change. Because that's the "barf ride" being discussed, not merely getting thrown to the back of your seat during initial acceleration.

That sounds even more fun. :D Although as the poster mentioned below, a passenger service would gradually rotate the passenger compartment to keep the G-forces vertical, a la a banking aircraft, so all you'd likely notice would be feeling heavier for a few seconds.

The analysis suggests that the speeds involved would require a few minutes of said g-forces, not seconds.

Re: Hyperloop Freight is a Joke

#176

Post by tjalfi »

cmrx64 wrote: post #17
Tade0 wrote: post #13

Here's an idea: Ditch the vacuum and instead put a mixture of 80% helium and 20% oxygen at half sea level pressure. This way you'll get a breathable atmosphere that is five times less dense than air and causes as much less drag. Imagine Teslas hurtling 155mph through these tunnels using only as much energy as if they were traveling at 85mph.

Where do you get all that helium?

The US government has been stockpiling it since 1925 in the National Helium Reserve (https://en.wikipedia.org/wiki/National_Helium_Reserve).

Re: Hyperloop Freight is a Joke

#177

Post by jheriko »

zerooneinfinity wrote: post #132
jheriko wrote: post #111

Earlier quoted context omitted.

be careful, tesla is not successful as a car company yet, and its not in good shape to become one either. one day it might be, and more generally i do hope that we see more progress in the electric car world... but for now tesla only turns a profit as a car company coupled with government incentives. even then, outside of the US (and inside actually) their market share is tiny or zero with very little growth. saying…

In terms of their mission statement which is convince people that electric cars can be 'cool', practical and inexpensive he has succeeded much more than you are giving him and the people at Tesla credit for.

fair enough, but its a different metric of success. :)
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