Have you heard of that fascinating new technology out of Arizona State: a jet pack-like device that allows a wearer to run faster through the wonders of space age technology? It's a lot like something tried and discarded in the 1950s.
The notion that you should be able to strap something to your back and fly has been one of those mirage-like concepts which tease us gravity-bound humans, so much so that entire books have been written on it.The story of "jet packs" often begins with a mention of The Skylark of Space, a sci-fi story which was illustrated with a rendering of a jaunty fellow wearing some kind of flying device on his back. That was 1928, which I only point out for context.
During the Cold War, the US government hinted it might be interested in purchasing jet pack technology if someone would kindly come up with something that worked. The best and the brightest immediately got right on it. While everyone has seen the rocket belt which was the most visible result of this low-altitude-space race, there were other entries which fell by the wayside. A patent search reveals that an inventor filed on a wearable man-rocket in 1945. Subtract the skis from these pictures and you might see a parallel with the ASU device,
The inventor with the ski fetish - as far as we know - never developed this beyond the patent stage but others took up the concept and ran with it. (<- Ha!) In 1958, a company called Thiokol developed two variations of this which they called "jump belts." The first device consisted of a tank which was worn on the back, filled with compressed nitrogen. The operator worked a throttle which blasted the gas out nozzles behind the wearer, pushing the person forward. Don't take my word for it; check out these official drawings.
They claimed this device would create 350 pounds of thrust for five seconds and allow its wearer to run at 22 MPH, albeit for a short period of time. After testing, Thiokol scrapped the device. It seems that the device was too bulky for what little benefit it added. They moved on to a different device: a belt of solid fuel rocket canisters which the wearer could fire as needed. They exhausted through downward facing nozzles, creating thrust which augmented the wearer's motion. The canisters could be fired simultaneously or in sequence, depending on whether one was looking for power or longevity.
This wearable propulsion device could, according to the maker, allow its wearer to jump horizontally 50 feet or vertically into a second story window. Interestingly, when Thiokol pitched this jump belt to the military, they claimed it would also allow a wearer to run at 35 MPH by using the belt to augment the action of running.They claimed that if the canisters were fired one at a time, they would provide a minute's worth of thrust.
Thiokol ran some tests which, for the most part, they kept under wraps. They tried to get the government to buy the devices. No one ever bit and the project fizzled as others moved on to slightly more practical rocket belts. This despite the really high-tech illustrations they created to explain how the device would work even when swimming.
Admittedly, Thiokol probably stretched a bit with its claimed results for the jump belts. If someone actually did run at 35 MPH wearing one of these belts, wouldn't they have filmed it? (By comparison, Usain Bolt hits a peak speed around 27 MPH.) And, how cool would it have been to see someone jump up into a second story window?
Even so, the gains from such a device - if it worked - would have been incremental at best. Especially when you consider the difference between a laboratory and a battlefield. It would be nice if we could strap a "jet pack" to a soldier's back and have him outrun Usain Bolt. But what happens when you load that soldier down with the various tools of his or her job? (Refer to photo of soldier, above.)
And that is the real problem here. Ever run down a really steep hill? Gravity "augments" your run so you go faster. Imagine a pile of equipment on your back as your augmented run speeds you down the hill. You still have to keep your body balanced over your legs. Try not to trip. Which is what will happen as this whole jet pack-rucksack- running soldier conglomeration barrels along, being pushed by a jet pack over a real world surface.
There are also quite a few questions which are not answered in the promotional video created by ASU, some of which probably have the wrong answers. For example, one of the biggest limiting factors in the Bell rocket belt was fuel capacity. An operator could only carry enough for a 21 second flight. The photo at the top of the piece shows a test subject running for 25 seconds. Was the engine running the whole time? If so, how long can it run?
Will American soldiers be zooming around the battlefields of the future, augmenting their movement with a running-man jet pack? We should wait and see before making crazy predictions. But I would argue for tempering our expectations: others have gone before us and tried similar things. We can learn from them.
I am not saying one way or the other whether this latest iteration of the "jet pack" will ever work. I would just advise against holding one's breath in the meantime. There are people at Thiokol who have been holding theirs for 56 years now.
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Steve Lehto is a writer, professor and attorney. He wrote The Great American Jet Pack: The Quest for the Ultimate Individual Lift Device and Chrysler's Turbine Car: The Rise and Fall of Detroit's Coolest Creation.