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Comment by Scaevolus | Hacker News Reader

The proposed Hyperloop's operation is quite different from a pneumatic tube, which forces objects through with air pressure. The design document explicitly describes the limitations of pneumatic tubes:

"At one extreme of the potential solutions is some enlarged version of the old pneumatic tubes used to send mail and packages within and between buildings. You could, in principle, use very powerful fans to push air at high speed through a tube and propel people-sized pods all the way from LA to San Francisco. However, the friction of a 350 mile long column of air moving at anywhere near sonic velocity against the inside of the tube is so stupendously high that this is impossible for all practical purposes."

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The 1950 prediction of a vacuum tube train a little closer?

The Japanese started dreaming of "high speed trains" in the 1940's.

http://en.wikipedia.org/wiki/T%C5%8Dkaid%C5%8D_Shinkansen

Their first "bullet trains" were started in 1959 and finished in 1964. A bullet train in those days was 130 mph (210 km/h).

I guess the world is a lot more complicated these days.

Also from the design document: Another extreme is the approach, advocated by Rand and ET3, of drawing a hard or near hard vacuum in the tube and then using an electromagnetic suspension. The problem with this approach is that it is incredibly hard to maintain a near vacuum in a room, let alone 700 miles (round trip) of large tube with dozens of station gateways and thousands of pods entering and exiting every day. All it takes is one leaky seal or a small crack somewhere in the hundreds of miles of tube and the whole system stops working.

Right. The Hyperloop's technical innovations are twofold: a tube with low-pressure that can be maintained with industrial-grade pumps rather than vacuum, and an air bearing to support the vehicle rather than maglev.

My first thought is what happens if the airflow in the air bearings is disrupted? Could the turbulence lead to a crash?

Even if it's not the same as the hyperloop I still find it very interesting to see that similar ideas have already appeared in the 1950's and obviously not been executed.

I saw this talk a while back by Peter Thiel ("You're not a lottery ticket")* where he specifically mentions the decline of big infrastructure projects, beginning around the 50's-60's. (I don't know how true this claim is though, since I haven't really studied the development of infrastructure in the USA in the 2nd half of the 20th century).

I often wonder if Elon Musk could be more than just a guy making money off of awesome ideas but also a catalyzer for bigger societal changes as far as optimism in big infrastructure and future investments is concerned.

*http://www.ustream.tv/recorded/29931127?utm_campaign=t.co&ut...

If you like the engineering ideas of yore you should get your hands on a copy of "Engineer's Dreams" by Ley. It's full of delightful megaprojects, some of which, like the channel tunnel, have actually become reality by now.

We probably had to pick between big infrastructure projects that benefited ordinary people (e.g. bridge maintenance, universal health care) and big infrastructure projects for the military industrial complex (e.g. a bewildering variety of fortified / mobile / densely packed / widely spaced ICBM launchers, enormous early warning systems, fleets of bombers capable of flying high or low, fast or slow around the world and back with multiple thermonuclear weapons, enough aircraft carriers to control the world's oceans and rotate for maintenance and shore leave, an even larger number of nuclear submarines to launch ICBMs, hunt rival submarines, perform covert intelligence-gathering missions in "enemy" waters, and protect the aforementioned aircraft carriers, SDI, etc.).

You can only spend more money on the military than the rest of the world combined and undertake so many other projects.

> The proposed Hyperloop's operation is quite different from a pneumatic tube, which forces objects through with air pressure.

The Hyperloop is similar to a pneumatic tube in much the same way the Segway is similar to a scooter.

Except scooters are wildly more practical than Segways, and a pneumatic tube at the proposed scale simply doesn't even look good on paper.

It's not meant to be a perfect analogy. It's more about the disappointed, underwhelmed feeling I got when I finally learned what the thing was. :(

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