Hyperloop Freight is a Joke • Hacker News Board

Re: Hyperloop Freight is a Joke

#161

Post by emodendroket » Mon, Oct 31, 2016, 10:52 AM UTC

woodpanel wrote: post #67

bigger_cheese wrote: post #57

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…

Well the article's author could have put more emphasize on the inflexibility, but reading the Parts on airfreight and trucks I think he got the gist of it. Good read. Concerning "barf rides": wouldn't Strong and well-timed anesthetics help?

Yeah, let's just fill the cabins with laughing gas; can't see any way that could go wrong.

Re: Hyperloop Freight is a Joke

#162

Post by imaginenore » Mon, Oct 31, 2016, 11:32 AM UTC

aaron695 wrote: post #157

imaginenore wrote: post #18

Earlier quoted context omitted.

That's a strawman. Most of the criticisms are technological and security related. How do you keep an enormous vacuum tube with fast-moving pods inside secure against even simple attacks?

? Derail a train = put a rock on the tracks.

That will maybe derail one train. Versus the whole tube exploding at the speed of sound and/or the shockwave hitting every pod traveling at speeds designed for near vacuum.

Re: Hyperloop Freight is a Joke

#163

Post by notahacker » Mon, Oct 31, 2016, 12:14 PM UTC

bwilliams18 wrote: post #98

notahacker wrote: post #51

Earlier quoted context omitted.

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…

Maybe I'm totally unaware, but don't trucking, air freight and sea freight have the same problems w/ regards to weight requirements and movement of goods in transit? Is this not a solved problem? Build Hyperloop Freight to fit a ULD and we're all set no?

As the article notes, goods would move a lot more when they're subjected to the G-forces of a hyperloop than the occasional rolling of a ship or even much milder G-forces of an aircraft taking off, which they have to be packed pretty carefully for as is. And whilst all transport methods have a weight limit and some degree of load-balancing requirement, it's much more of a restriction for the load of a capsule fired at supersonic speed through a curving tube that has to resist forces imposed upon it than a bigger lorry chugging along at a sedate 60mph.

Re: Hyperloop Freight is a Joke

#164

Post by Retric » Mon, Oct 31, 2016, 1:58 PM UTC

toomanybeersies wrote: post #134

Retric wrote: post #121

Earlier quoted context omitted.

Really it's just a question of track design as these are 100% predictable G forces. If you really need to turn you can just roll the cabin and keep these g's directly under you and or slow down apraoching it. Elevators can also quickly have a fairly wide range (0.8 to 1.2) g's and people don't really get sick in them. Highways for example have fairly wide banks which people rarely notice. https://sterlingpearce.files…

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.

Re: Hyperloop Freight is a Joke

#165

Post by dpark » Mon, Oct 31, 2016, 2:53 PM UTC

imaginenore wrote: post #22

dpark wrote: post #15

Earlier quoted context omitted.

Why would loss of vacuum necessarily result in loss of life? I would expect loss of vacuum to result in sudden deceleration, but not with a deadly level of force.

1) Because the pods are not designed to go that fast through the air. 2) Because in the case of an explosive recompression there might not be a tube anymore.

This is a hollow answer. "Not designed for" is an absurd claim for a thing still in prototyping. Same for the "explosive recompression" claim. You're making this claim about a system that doesn't exist.

I'm not bullish on hyperloop but I see no reason to believe that the engineers can't design a pod capable of not disintegrating in air, or capable of designing a track with a failure mode better than completely falling apart.

Re: Hyperloop Freight is a Joke

#166

Post by dpark » Mon, Oct 31, 2016, 2:59 PM UTC

nickparker wrote: post #75

problems wrote: post #16

Earlier quoted context omitted.

Air being drawn in results in pressure on the capsule, propelling it. Check the video out for a demo.

There are three mitigating points for that issue: First, you would get choked flow at the inlet, and if you do the math it actually takes a massive opening to really make a dangerous shockwave. Eg, if a joint in the tube disconnects and the two halves pull apart, the inlet area is the tube circumference * gap between halves. The two halves would need to separate by the full diameter of the tube (~15 ft) to get full a…

Seems like you could also solve this with blast gates. If the tube breaks open behind the train, slam a gate closed to stop additional air from entering. There'd likely be air in the tube already, but with no additional supply, the propellant force would diminish rapidly.

Re: Hyperloop Freight is a Joke

#167

Post by dpark » Mon, Oct 31, 2016, 3:04 PM UTC

problems wrote: post #16

dpark wrote: post #15

Earlier quoted context omitted.

Why would loss of vacuum necessarily result in loss of life? I would expect loss of vacuum to result in sudden deceleration, but not with a deadly level of force.

Air being drawn in results in pressure on the capsule, propelling it. Check the video out for a demo.

Okay, I was assuming a failure in front of the train. If the failure is behind the train, it's still an extremely solvable problem. Blast gates to stop the inflow of new air. Or inject air in front as nickparker suggested. I don't see that this is a legitimate blocker to this technology.

Re: Hyperloop Freight is a Joke

#168

Post by Manabu-eo » Mon, Oct 31, 2016, 3:58 PM UTC

imaginenore wrote: post #162

aaron695 wrote: post #157

Earlier quoted context omitted.

? Derail a train = put a rock on the tracks.

That will maybe derail one train. Versus the whole tube exploding at the speed of sound and/or the shockwave hitting every pod traveling at speeds designed for near vacuum.

Physics 303: "pipes are not lossless! Friction and viscous interactions between the entering air and the tube wall will slow down that "shock front" to a highway speed wind in only a couple km." (quote from schiffern post). You may want to look at derivatives of Bernoulli's equation, like Darcy–Weisbach equation.

Plus there is a planned emergency repressurization of the whole tube that would eliminate even that medium speed shock front. Plus a small 10cm diameter bullet hole would imply in less than 1% of the flow of a completely broken tube (a much harder feat to do), per laws of conservation of energy and matter.

As pods travel with 4km or so of separation, at most one pod will be affected. That is much less people than a derailed train.

Re: Hyperloop Freight is a Joke

#169

Post by ant6n » Mon, Oct 31, 2016, 4:45 PM UTC

icebraining wrote: post #99

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.

Then you'll be glad to know that's what he's doing with Hyperloop - he has just released the idea as a paper, but he's not directly involved in its development, which is being done by independent companies.

You mean he released a paper renaming vactrains to hyperloop.

Re: Hyperloop Freight is a Joke

#170

Post by Manabu-eo » Mon, Oct 31, 2016, 5:05 PM UTC

na85 wrote: post #26

weego wrote: post #4

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.

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.