USA TODAY - The world has had a day to digest Tesla and SpaceX CEO Elon Musk's proposal of a "hyperloop," a high-speed train that would shoot pods through a tube with air pressure at speeds that would take people from Los Angeles to San Francisco in 30 minutes.
And he is mostly being hailed as a visionary, an example of the kind of can-do spirit that America needs.
But not all think the idea he is supporting is feasible -- pointing out that traveling faster than a jet aircraft in a tube would be really, really difficult.
Sam Jaffe, writing on the Navigant Research blog, says that after reading Musk's 57-page proposal that he sees some very big hurdles.
"The biggest concern with this plan has to do with temperature. The pod will be compressing air and expelling it downwards and backwards. All that air compression creates an enormous amount of heat, which can damage the pod and its machinery," Jaffe writes.
He notes that Musk proposes that every passenger pod carry a water tank, which would provide a coolant. The water would turn to steam that would be released at stations. But he questions whether a pod would be able to carry enough water to do the job.
Likewise, the pods would be under a lot of stress. And if the tube structure is elevated, it could be subject to buffeting by winds.
Musk's idea isn't new. Ever since pneumatic tubes using negative air pressure to shoot capsules through tubes showed up decades ago -- department stores used them for transactions and newspapers used them to carry stories from the newsroom to operators that would produce metal type for the printing presses -- people have dreamed of traveling through cylinders at high speed.
Jay Yarow, writing for Business Insider, says a similar idea for transporting passengers was hatched 41 years ago by a Rand Corp. researcher, R.M. Salter. He called his hyperloop a "Very High Speed Transit System," or VHST. It, too, depended on trains suspended in air running through tubes. He says it faced technical challenges, but there were no apparent insurmountable barriers. His system would have been airtight, unlike Musk's.
The idea went nowhere.
And Musk is not proposing to take on this futuristic train idea himself, having enough on his plate now with his Tesla car company and SpaceX space technology company. While he put his own fortune on the line for those, Musk will be sitting back to see if his support helps get this idea advanced in the hands of others.
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