The historical Hyperloop: an examination of the technological ancestry of alternative high speed rail part 2 of 2

Written by Chris Miller

So much of the HYPE in the Hyperloop comes from the man behind it. Elon Musk, modern tech demi-God of PayPal, of Tesla, of SpaceX, seems to guarantee the success of a technology simply by adding his name to it. So when he put his name on a 2013 white paper espousing a “new” technology called the Hyperloop, everyone noticed. But even within that white paper Musk admits, without giving away too much credit, that this is an old idea. In this, the second part of the Hyperloop Research Group’s History of the Hyperloop, we will explore the 20th century ancestors of the Hyperloop, the innovators behind those technologies, and their eventual failures.

Robert Goddard may not have ever had Musk’s charisma or his fortune, but what he lacked in media savvy and cash he made up for in brilliance. He was an engineer ahead of his time, and his contributions to science earned him a significant place in history. His name, now officially commemorated in the naming of NASA’s Space Flight Center in Greenbelt, MD, is primarily associated with landmark innovations in the use of liquid rocket fuel (Garner 2015). However, two decades before his genius was recognized on a wider scale, Goddard proposed a technology that, after a century of further contributions by other engineers, would serve as a canonical document for current work on the Hyperloop.

At the turn of the century, nearly 30 years after the failure of Beach’s Pneumatic Transit, a young Goddard was challenged to envision the future of transportation by a college professor. Rather than languishing in a file cabinet though, that short paper took on a life of its own, eventually finding its way into Scientific American (the same magazine from which Beach gleaned ideas about his own invention in the 1860s). In that 1909 article, “The Limit of Rapid Transit,” Goddard laid out many of the foundations of the Hyperloop, including an evacuated tube, some sort of capsule suspension (he suggested magnets, now commonly used on other high speed rail technologies), and a formula for acceleration (Goddard 1909). As Goddard shifted his interests to rocket propulsion, these ideas lingered in the background, eventually patented by Goddard in 1945 as the “Vacuum Tube Transportation System.”

In the 60 years after Goddard published his paper, innovations in transportation were centered around the hallmark technologies of the 20th century: the automobile, the plane, and space flight. However, in the ‘70s, perhaps driven by escalating traffic and fuel costs, ideas about alternative rail travelled began to re-emerge, including tests of long-standing hypotheses about maglev (short for magnetic levitation) trains in Japan (usjmaglev.com). However, more pertinent to the history of the Hyperloop were the “Aerotrain” and “Planetran,” developed by Jean Bertin and Robert Salter, respectively.

The Aerotrain, developed in France in the late 1960s, was one of the first full-scale experiments in compressed-air “levitation” technology now planned for the Hyperloop (Hollebone 2012). Similar in appearance to a monorail, the limited friction produced by the rudimentary air bearings allowed for high speeds to be maintained, actually breaking rail speed records at the time. Despite promising tests, high infrastructure costs and a string of costly accidents ended government and private support for the Aerotrain in the late 1970s. Despite this failure, Bertin’s work was effective as a proof of concept in respect to the value of compressed air as a means of reducing friction.

At almost the same time, Dr. Robert Salter, working for the RAND Corporation, wrote two detailed white papers that described his Planetran (Salter 1972, Salter 1978). At first blush, the Planetran is almost identical to the Hyperloop as it is designed today: an evacuated tube, small passenger capsules, electromagnetic propulsion. There are some key differences, namely the reliance on maglev technology (rather than air bearings), a fully evacuated tube (as opposed to partial vacuum), and a subterranean route (instead of elevated tracks). It was these differences that likely led to the Planetran never becoming a reality: maglev technology was still in its infancy; maintaining a hard vacuum across thousands of miles of track is technically unfeasible; and tunneling the length of the track was cost prohibitive.

Across these brief historical accounts of relevant technologies, there is one theme: failure. These technologies seem to represent dead ends, tombstones in a graveyard of innovation. But if they were dead, the Hyperloop seeks to resurrect them. The number of factors that must be just right for a technology to gain a cultural foothold is innumerable, and perhaps the circumstances are only now just right for this particular conglomeration of technologies. With plans recently announced to begin construction on a Hyperloop test track next year, we will soon have the opportunity to observe the fate of this most recent iteration in real time. Whether that fate will look more like the model –T or the abandoned skeleton of the aerotrain, only time will tell.

Garner, Rob. “Dr. Robert H. Goddard, American Rocketry Pioneer.” Text. NASA. N.p., 11 Feb. 2015. Web. 24 Apr. 2015.

Goddard, Robert. “The Limit of Rapid Transit.” Scientific American 20 Nov. 1909. Web. 2 Apr. 2015.

Hollebone, Ashley. The Hovercraft: A History. The History Press, 2012. Print.

Salter, Robert M. “The Very High Speed Transit System.” 1972. Web. 6 Apr. 2015.

—. “Trans-Planetary Subway Systems.” 1978. Web. 2 Apr. 2015.

Photo from:

Salter, Robert M. “Trans-Planetary Subway Systems.” 1978. Web. 2 Apr. 2015.

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