Sunday, December 14, 2014

#349 / Hyperlooped

Elon Musk, the futurist head of Tesla Motors and SpaceX, thinks it would be a great idea to build a person-sized pneumatic tube connecting major population centers, so people could sit back and be delivered to their selected destination at about 760 miles per hour. This idea has a name, the "Hyperloop."

According to a recent article in The Atlantic "City Lab," an architect and designer associated with UCLA, who is spending a year studying the concept, has called Musk's idea "insane."

It's a little unclear what Craig Hodgetts means by this statement, however, and the remark may be intended to be something along the line of "that's insane, man," meaning "really good."

Everything checks out, according to Hodgetts, as far as the physics and engineering are concerned. He thinks the main problem may be that taking a ride on the "Hyperloop" might make a rider nauseous. The "City Lab" article opines: 

The forces exerted on the body are so great that seat design and panel displays are almost as important as the physics behind the locomotion. If you build it, the passengers will come — but only if the Hyperloop doesn't make people want to throw up.

My own thought, putting aside concerns about the physics of the system, and its possible nausea-inducing qualities, is that I don't think I would really like to put myself into a closed pneumatic container (no windows, I think!) to be fired at 760 miles per hour towards my chosen destination. By car, plane, or train, I'd get to see the scenery. I kind of like that concept. Turning myself into a package or a projectile, to save some time, is just not my idea of a good thing to do.

I like to say (and it's true) that we can do "anything" we want to in our human world.

But just because we "can" do something, doesn't mean we should!

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  1. What can you possibly hope to learn by "putting aside concerns about the physics"? Overcoming the Kantrowitz limit is the only qualitative difference between this technology and your typical bullet train. If you don't understand the physics, you don't understand the Hyperloop.

    1. Propulsion. Hodgetts says "Hyperloop is the same thing as the pneumatic tube." [1] This is false. Pneumatic tubes move an inert object using pressure differential [2]. The Hyperloop does the opposite. It actively sucks in the already thinned air in front to reduce drag from the forward envelope and by providing levitation. It's "... moving motor element (rotor) will be located on the vehicle for weight savings and power requirements while the tube will incorporate the stationary motor element (stator) which powers the vehicle." [3] This is not new! Powered rails have been in use since 1886 [4]!

    2. Acceleration. "These bend radii have been calculated so that the passenger does not experience inertial accelerations that exceed 0.5g. This is deemed the maximum inertial acceleration that can be comfortably sustained by humans for short periods." [3] This is similar to passenger aircraft [5]. Even the 2013 Tesla Model S can do higher acceleration from 0 to 60 mph [6]! By the way, motion sickness comes not from the *magnitude* of g-forces, but from low frequency *changes* in acceleration [7]. Track pylons decouple the tube from ground features, eliminating deviation from the gentle curving geodesic paths which, along with the levitating air cushion, entirely eliminates low frequency vibrations. It's a solved problem.


  2. Just because something is *new*, doesn't mean we shouldn't do it!

  3. We shouldn't do it because it's unnecessary, squanders critical energy and natural resources and promotes economic growth and consumption.

  4. Care to back up those opinions with evidence?

  5. Based on currently feasible transportation systems, it is my opinion that the described ultra high speed transportation system is unnecessary, will squander critical energy and natural resources, and will promote economic growth and consumption.


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