SpaceX Is Building a Hyperloop Test Track

Jason Koebler reports that SpaceX is building a small-scale version of Elon Musk's hyperloop transport tube system, which can move cargo and people at speeds over 700 mph. The test track will be approximately one mile long, and its inner diameter will be between four and five feet. But while SpaceX is building the track, it's not going into full development mode. Instead, the company is turning it into a competition. Other organizations will be invited to build pods — the containers that move through the tubes — and test them inside the track. They say the competition will be geared toward university students and independent engineering teams. SpaceX expects the testing to happen next June, and they've published a document with details on the competition. They add, "The knowledge gained here will continue to be open-sourced."

Comments

Re:LOL ... awesome ...

[JaredOfEuropa]

You're right of course. That leaves the lawyers...

To head off the Hyperloop misconceptions...

[Rei]

1) It's not a vactrain. It's not even that similar to a vactrain. It functions like a very high altitude aircraft, with such rarified air (and the ground-effect surface for lift) being provided by a tube. Nothing is "sucking" or "pushing" it, and nor is it maglev. The compressor at the front exists to stop a column of higher pressure air from building up in front of it, not for propulsion.

2) It is not a train. Rates for building train tracks, rail bridges, etc, are not applicable. Of human structures it's most similar to, an oil pipeline is the most apt comparison - very long, continuously welded elevated tubular steel segments capable of withstanding a pressure differential. It has some disadvantages versus a pipeline, such as much tighter tolerances, as well as some advantages, such as not containing environmentally-hazardous flammable materials. A full comparative list is too long to go into at the moment.

3) Like a pipeline and unlike rail, costs for elevating it are significantly reduced because it doesn't experience wide load swings. The cars are an order of magnitude lighter than a high speed train and thus exert an order of magnitude less loading as they pass (and only briefly). The difference in throughput is compensated for by much higher launch frequency via computer control. With dramatically reduced loading comes dramatically reduced support structure costs - more akin to the supports on the Disney Monorail than that of a rail bridge.

4) It is not meant (as per the source) to be an exact replacement for rail; it's meant to be an intermediary transportation system between rail and air travel.

5) Yes, the original design has flaws. No, none of them are fundamental. Yes, the concept can be significantly improved upon.

Back to your regularly scheduled thread.

Re:To head off the Hyperloop misconceptions...

[Rei]

On the front of how the concept can be significantly improved upon, here's one: pumping is a very small fraction of the total costs. You could significantly increase the pumping and not have a significant impact on the costs. If you increase the pumping by, say, an additional 4x and inject water vapor, then you will achieve an 80% water vapor atmosphere (water does not condense at such low pressures). This offers a ~40% increase in the speed of sound and thus the maximum speed of the vehicle and reduces its resistance at a given speed.

One can take it further and inject hydrogen instead of water vapor. Most of the downsides that immediately come to mind don't actually turn out to be problems in practice - at such low pressures it's not flammable even if mixed with air, such low pressures aren't an embrittlement risk, the quantity of hydrogen needed is trivially small and thus costs little and poses little ozone hazard, etc. It's basically still "nearly a vaccuum", just with trace hydrogen rather than trace air. Pure hydrogen allows a maximum velocity nearly 4x that of the standard Hyperloop approach.

(Helium is another option, though not quite as good as hydrogen and more expensive. Also, if one wants to go faster and with less resistance than hydrogen, then there's only two options: 1) hot hydrogen, and 2) hard vacuum with maglev (aka, not hyperloop))

Re:Reasons why I don't like Musk's hyper loop

[nine-times]

These seem like they may be valid complaints, I don't know. But you're complaining about something in the prototype/proof-of-concept phase. If it works, then they can go about trying to turn it into a practical method of transportation, but at this point, we may as well be complaining about what color it is.

Re:Reasons why I don't like Musk's hyper loop

[Rei]

1. All the diagrams give the impression that it will be like people flying through tubes as in Futurama. Instead you will be sealed inside a metallic "bullet", that runs in a metallic tube - no windows for you (sort of like James Bond in The Living Daylights).

Rather than windows, it's to have large digital wall displays that show the outside as if you had giant picture windows. This is the direction airplanes are looking to move in the future as well. Tests run by researchers have shown it to be well received by passengers.

It's a pity if you have any sort of claustrophobia.

The seats are actually quite roomy - check out the dimensions in the Hyperloop alpha document.

2. While the device doesn't run in a complete vacuum, it runs in an atmosphere that is low to the point of being unbreathable. But the device doesn't contain any onboard air supply

Yes, it does. Section 4.5.2. Same system as on an airplane.

3. There was no indication that the loop itself was anything more than a single tube.

It's two tubes, one for each direction. In the event of a long term outage, the one open tube can be periodically reversed to allow traffic in both directions, at a cost of throughput.

So if a device fails, all devices that are already in transit and behind it are screwed (see 2 above).

All capsules have mechanical braking systems and are spaced five minutes apart, automatically triggered in the event of an obstruction. They also all have powered wheels for low-speed travel. Section 3.5.2.

It'd be nice if you'd read the document before complaining about the concept.

I heard

[Virtucon]

that Elon was going to name it the Ted Stevens memorial hyperloop

Let's be honest about the purpose of the hyperloop

[Bruce Perens]

Although the hyperloop is possible and might even be practical someday, let's please be honest about the reason it was created. Elon Musk just wanted to kill the California high-speed rail.

That might have been OK if there was a hope that we could actually replace it practically with a hyperloop. But given the history of bleeding-edge rail - ride any maglevs lately? We haven't even had much success with monorails outside of theme parks and Las Vegas - we don't really have any working system to replace high-speed rail. Hyperloop should really be called "Pipes that carry People" and we need decades of work on it before considering intercity lines.