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."

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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))