Follow Slashdot stories on Twitter

 



Forgot your password?
typodupeerror
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×

Comment Re:Distances (Score 1) 108

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) 108

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) 108

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) 108

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.

Comment Re:Use that low pressure air (Score 1) 108

Inductrac is less efficient than air bearings and the track is more complicated to build than straight pipe. That said, if the air bearing concept proved unworkable, I'd think it a fine fallback alternative.

The costs of the turbomachinery on the current design is factored into the budgeting. And you need it either way unless you're planning to run a hard vacuum, since otherwise the vehicle will compress the column of air ahead of it. Industrial air compressors aren't exactly new technology, although the operating environment is admittedly a bit unusual ;) But I do have to agree with their choice of focusing on air bearings. They're simple, light, equal or greater efficiency in comparison to magnetic, and most importantly they keep the "track" simple. The main downside is that they require a fairly high wall smoothness (hence Hyperloop Alpha's need for a rotary tube polisher).

Comment Re:Terrorist target? (Score 1) 108

If you're going to detonate bombs large enough to take out a concrete column for a big steel pipe, why wouldn't you do it where you'd kill a lot more people rather than "hopefully lucking into causing enough deflection (by increasing the span) right before the next capsule arrives that it can't decelerate sufficiently in time to handle said deflection, and possibly killing or injuring one capsule's worth of people"?

Airplane attacks were popular because of the ability to kill hundreds of people at once, or to hijack planes and use them as weapons. Not exactly applicable to Hyperloop. And even airplane attacks seem to be falling out of popularity, in favour of coordinated shootings and plowing through crowds.

Comment Re:Hornby set? Maglev is "new"? (Score 1) 108

If you think the pressure maintenance figures in the Hyperloop Alpha document are unreasonable, cite the actual numbers you disagree with and explain why.

The main advantages over air travel are that the pressure is much lower, frontal area much lower, allowable spacings far closer (no "air traffic"), no noise pollution, no air pollution, and efficient, direct acceleration of the vehicles, with the tube itself serving as a mounting point for the solar panels that power it.

You clearly have never read the Hyperloop Alpha design document. It does include diversion options. There are regularly spaced emergency exits across the track. Vehicles brake to a stop then roll on wheels to the nearest emergency exit.

As for security: the cars are about the size of monorail cars. So if you're going to assert random things about what security will be like, why not assert it'll be like monorail security?

Yes, the design fundamentally does not work if it's not driverless (you really should read the design document before discussing it).

The costs of tunneling are included in the budgeting in the design document (again, you really should read it). There is no "50km long 7,6m diameter undersea tunnel" leg to it.

Comment Re:Think of why maglev is expensive... (Score 3, Interesting) 108

Why are you under the impression that putting it in a tube makes handling turbing forces, stopping forces and control more difficult? Inside a tube, all motion is perfectly constrained, and you have a tremendous amount of surface area to magnetic brake against.

The turning radii issues are of course real, and are highly addressed in the Hyperloop Alpha document. Likewise for dimensional precision. For smoothness, their solution is a radial polisher which drives down the tube behind the pipelaying crew and smoothing out each orbital weld (and the pipe itself). For straightness, alignment is maintained by the same suspension/alignment system they use to deal with earthquakes.

As for why maglev trains are expensive - trains are expensive for a wide variety of reasons. Land acquisition and permitting is often the most expensive. Tunnels and viaducts are often a very large component as well. Maglev technology itself often tends to have high bills.

Hyperloop (as per Hyperloop Alpha, not the student competition) isn't maglev, it's an air bearing system. Skis, basically. The pipe is built the same as oil pipeline, and the budget is similar to that of oil pipeline budgeting per unit area per unit distance (oil pipelines have harder environmental issues to overcome and much higher loadings, more significant temperature management issues, etc, but lower precision / straightness requirements, so it's probably a wash). Tunnel cost is minimized by minimizing tube size (the budgeted tunnels are standard rates for tunneled pipe in non-urban areas). Viaduct costs are minimized by a key design feature of Hyperloop - minimizing peak loadings by having frequent, small vehicle launches rather than infrequent, large vehicle launches. Viaduct costs tend to track their peak loading.

As for land acquisition, the costs in Hyperloop Alpha are kept down by a combination of design and cheating. As per design, it's designed to be small enough to fit elevated into highway medians, with the low peak loadings, making overhead suspension an affordable option. Such places are state land, and already permitted for far more environmentally harmful activity (road traffic). This of course requires state buy-in to the concept, but states often specifically pursue high speed transport options. Private land acquisition is limited to places needed to maximize turning radii, and in-city for stations. The latter is the other place that they cheat - Hyperloop Alpha avoids cities. LA and San Francisco are served by it, according to the design, like airports on the outskirts of town; people have to get connecting legs into town. But that would be an unpopular decision, and you would expect the state to insist on greater accessibility (airports are only out of town because they have to be, not because that's a desirable location). Likewise it bypasses cities en route, unlike HSR. Basically, it's designed as something halfway in-between HSR and air travel (both in terms of service and throughput), but targeting much lower prices, higher speeds, and a lower energy footprint.

In short, it's budget savings vs. HSR are somewhat of a combination of cheating (cutting out a lot of what HSR does) and design (keeping track loadings down, profile small, build in the same manner as an established industry (pipeline), and moving your hardware (capital expense) through the system as quickly as you can.

Comment Re:Distances (Score 2) 108

Why?

Part of the whole point of Hyperloop is that the low pressures aren't extreme (it's not a hard vacuum), and are thus easier to maintain with a regular series of vacuum pumps. And it has no "joints" (the only interruptions being periodic emergency exits, and the pumps themselves). All of the pipe segments are orbital welded and then polished smooth.

Comment Re:Use that low pressure air (Score 1) 108

Wheels at low speed, not maglev.

Of course, the "Hyperloop competition" blurred the line as to what counts as "hyperloop" anymore, because it was based around a bunch of purely maglev options that were radically different from the Hyperloop Alpha design (in many ways beyond just the levitation means).

Slashdot Top Deals

You need tender loving care once a week - so that I can slap you into shape. - Ellyn Mustard

Working...