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Comment Re:Maintenance? (Score 1) 117

You cannot have people inside the tube at the same time as vehicles are in the tube regardless, so there's no point to conducting maintenance in a vacuum; you would simply repressurize it (aka, open valves at the pumping stations, or the emergency exits). But there's also no point to ever having people inside. There's nothing except for an accident to damage the inside of the tube; the vehicles do not touch the walls, and it's a very rarified atmosphere, so it's not going to rust from the inside. If there's any need from maintenance, it'd be a need from the outside.

There is one thing that I fault the initial design for, which is the proposal of a two-tube system. This means that if one tube has to go down for maintenance, you have to alternate the other tube between directions, and each time you switch it, wait for it to clear. This would be a big throughput loss. With a three-tube system, you can have the third tube follow whichever direction has the highest demand at whatever point in time, and when one tube goes out you can still keep bidirectional traffic going. Maybe have the third tube be a "stop halfway then continue" design so it can offer service to the valley, at lower speeds.

The other thing I fault the initial design for was for setting it up as a competitor to HSR, which was obviously going to invite a lot of anger against them, and while most of it is just by idiots who never bothered to read the design document, some is legitimate - in particular, that Hyperloop doesn't serve as many cities, or city centers (which they really should have done), like HSR does. I feel that they should have proposed LA to Vegas as the initial leg, so as not to stand in competition to HSR, and so there would be few cities in-between. It's also raise the concept of Vegas magnates funding it; the ability of LA residents to hop to Vegas in half an hour for cheap would be hugely beneficial to them.

As for going into cities: I know they wanted to give a very impressive price figure, and going into cities would have raised that, but as it stands, their price figure was so low that a lot of people refused to believe it (without ever looking at why it was low). A higher price figure because of going into cities would have both made people more credulous, as well as being a more useful, likely-to-be-funded system.

Comment Re:Designed initially by Elon Musk. Really? (Score 1) 117

... which did not involve anything remotely similar to Hyperloop.

Please learn how Hyperloop actually works before insisting that something else is the same. (hint: google "Hyperloop Alpha" and read the design document; it won't take all day). Hyperloop Alpha is neither maglev nor a vactrain; it's basically an extreme version of a ground-effect aircraft flying through a rarified atmosphere, using a compressor to prevent the buildup of a column of air ahead of it by shunting it to the air bearings and behind it - thus allowing it to operate at far-easier-to-maintain pressures and with much easier construction / lighter vehicle mass than maglev.

Comment Re:Hornby set? Maglev is "new"? (Score 1) 117

This is the standard way people complain about Hyperloop.

Step 1) Don't ever bother actually reading the design document, despite the fact that it's not that long and addressess the vast majority of arguments

Step 2) Compare Hyperloop to something not even remotely comparable to it, like the costs of building viaducts for an order of magnitude higher peak loadings, building tunnels with an order of magnitude or more greater cross section, acquiring orders of magnitude more private land, and comparing costs for building through cities with the costs of building through the countryside.

I'd have a lot more respect for its opponents if they'd actually read the design document and actually make comparisons to remotely comparable things. As it stands these threads usually just make me want to hit my head on the wall. At least you recognized the absurdity of the comparison being made.

Train tunnels have to be big. Not only because trains are big to begin with, but because the tunnel walls can't be anywhere the train, or the train will push a big column of air ahead of it, eating energy and slowing it down. Hyperloop tunnels are like aquaduct tunnels - no larger than that of the pipe. Which is sized for capsules, in the non-vehicle version, of two people side by side in First Class-style, semireclined seats.

Comment Re:Distances (Score 1) 117

Peak loadings from the tube are significantly lower than from the cars (I've done the math, feel free to double check for yourself). And a Hyperloop car weighs about an order of magnitude less than a train. The peak loadings are vastly lower.

The amount of track steel per unit length isn't that great; if you were just buying raw steel the cost would be something like a fifth of what's being budgeted for buying the pipe segments for the tube. Rail isn't expensive because steel is expensive; it's way, way down on the list of costs.

Maglev cannot be faster, as it has to plow large amounts of air out of the way (particularly problematic in tunnels - which means that they have to significantly increase tunnel diameters, which significantly increases tunnel costs). The only limitation to Hyperloop speed is the speed of sound in the tube - which can be increased if needed, as discussed elsewhere in this comments section. The amount of vacuum needed is many orders of magnitude less stringent than what you'd normally consider a "vacuum"; it's about a thousandth of atmospheric pressure, versus the millionths or billionths of atmospheric pressure in hard vacuum systems - and thus thousands to millions of times easier to maintain.

Hyperloop is relying on being able to exceed the normal speed of sound without a sonic boom due to the lower air pressure,

The speed of sound does not work that way.

Comment Re:Distances (Score 1) 117

It's not "picking numbers". For god's sake, why does everyone see fit to argue about a system without having read the design document for said system? All of the cost breakdowns are there. It's not that long of a read. It's fine to disagree with something when you know what it actually is you're disagreeing with, but it's ridiculous to assert that something is wrong when you don't even know what that thing is.

Comment Re:Distances (Score 1) 117

The length of the tube expands and contracts dumbass.

Why are you writing that, "dumbass", as if I didn't write precisely that, and explain precisely how it's accounted for as per the document?

The tube expands and contracts. This is accounted for by changing bend radii and changes in length of the tube as a whole at the endpoints.

Also, why are you of the impression that inserting words like "dumbass" into your posts makes you sound more intelligent?

Comment Re:While I'm not exactly one of his biggest fans.. (Score 1) 40

I'd argue that while there's not compelling arguments for "because we can" programmes, there's a very compelling argument for having lofty goals in mind and properly funding those goals. And if those goals include a long-term presence offworld, then that funding means both a robust robotic exploration program, a large systems engineering programme, and most importantly a very sizeable launch cost reductions programme, both the conventional, short term (getting rocket costs down) and unconventional, long-term (exotic forms of launch).

0,5% of the US federal budget plus pittiances from the rest of the world, combined with ever-shifting congressional make-work mandates, does not cut it. 1% plus plan buy-in from congress (particularly those on important committee seats and those in stable seats that are likely to be around for the next 10-20 years), would probably do it. And the rest of the world needs to get off its arse on the space front. Roscosmos's budgets are a shadow of what they used to be. China's space industry is booming, but still relatively small. JAXA's could use to be better. ESA's is tiny compared to the size of the EU economy. But I guess people don't see it as a priority - even though the public thinks we're spending vastly more on space than we actually are and are by and large okay with that.

Comment Re:Distances (Score 1) 117

Technically you can scale Hyperloop to several times higher speeds, if you can build sufficiently straight segments (e.g. Great Plains). It does however require one alteration of note: you have to increase your leak compensation pumping capacity severalfold (it's an unknown at this point how bad leaks will be, though they tried to be pessimistic in their assumptions), while injecting hydrogen or helium to maintain the same pressure. Ideally hydrogen (it's not explosive nor embrittling at such tiny pressures, although its behavior when compressed would need to be studied). You need light gases to raise the speed of sound inside the tube (also reduces air resistance / compressor mass throughput requirements). Water would work also instead of hydrogen or helium (it's a gas at those pressures), although not as well (but better than air).

At least, pessimistically it's required. I don't think they've done anything to simulate what sort of temperature the rarified gas inside the tube would maintain under full load (the effect of passing vehicles on the tube itself is trivial - the gas is a terrible conductor of heat, and the tube has a huge convecting surface area). If the rarified gas was left significantly hotter than the tube (due to its poor conduction of heat), that too would raise its speed of sound.

Comment Re: Distances (Score 1) 117

Same solution Japan uses for high speed rail. You're in a tunnel. Now you're out and instantly on a bridge! Now you're off and instantly in a tunnel! Now a bridge! Tunnel! Bridge! Tunnel! Bridge! (repeat until you arrive at your destination)

That said, tunnel costs are proportional to diameter and bridge costs proportional to peak loading, so a Hyperloop-style system wouldn't be such a bad idea in such an environment.

Comment Re:Distances (Score 1) 117

A more detailed breakdown of the differences versus high speed rail in general is in this post.

As for versus maglev: maglev is even more expensive to construct than conventional high speed rail, and suffers from the same design challenges that Hyperloop is designed to eliminate. Beyond that, Hyperloop is entirely self-powering - it uses so little power (coasting the vast majority of the time) that it's easy to have enough solar panels atop the tube to provide for its energy needs. Anything not in a rarified atmosphere moving at those sorts of speeds is plowing against a large amount of air resistance.

The small size of Hyperloop cars is a feature, not a bug; it's not just the cross section that's kept down, but the length as well. By keeping cars small (but frequently launched for equivalent throughput), they minimize peak loadings. Viaduct costs are roughly proportional to peak loadings. Elevation allows them to reduce a huge amount of overhead costs (the majority of the costs of a typical rail project) and eliminates a lot of the technical challenges with HSR involving ground shifting and earthquakes, transferring all of your support to readily adjustable fixed points.

As for passenger comfort, the interior looks more comfortable than any train I've ever been on. Of course, you can't get up and walk around, but then again, trips are so short there's not really any need to. I would say that the excellent leg room would be great for stretching out for napping, but that would be a very short nap ;)

As for loading, multiple capsules are loaded up at once. It's not a one-at-a-time thing.

Comment Re:Distances (Score 2) 117

What is so difficult for you about reading the design document, "dumbass"? Did you really think that that isn't covered? Section "Earthquakes and Expansion Joints". The tube is not firmly affixed to each pylon; it's mounted on a multiaxis damper. Its positioning is automatically controlled relative to independent factors, including earthquakes, ground shifting over time, and daily thermal expansion (which results in planned for anticipated changes in bend radii as well as a net overall expansion or contraction at the endpoints)

What it is about some topics that convince people to go online and write rants without having read the design document? It's not that long, for crying out loud. It's one thing to disagree with a particular engineering decision. It's an entirely different thing to have no clue what the engineering decisions are but still rant anyway.

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