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Wednesday, May 25, 2011

JetLev Water-Powered Jetpack


I saw this article in Popular Mechanics (http://www.popularmechanics.com) about a new toy being developed to replicate a jetpack but by using water. Very interesting. Honestly, I would not want to try it.

Full article: http://www.popularmechanics.com/outdoors/sports/watersports/jetlev-water-powered-jetpack-test-flight-exclusive-video-5525115


Below is an excerpts of the article for your reading pleasure.
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Clearly, the purpose of science is quite simple: to provide humanity with jetpacks. Yet so far it has failed to deliver. Sure, there have been rocket belts, like the one seen in the 1965 James Bond film Thunderball. But the expensive, difficult-to-use hydrogen peroxide propellant is only good for about 30 seconds of thrust, relegating the technology to the status of curiosity.



Finally, things are changing. Starting next month, a Florida-based company, JetLev, will begin delivering the first commercially available jetpacks. JetLev invited PM to be the first publication to experience the technology firsthand by taking a unit for a test-fly. So this past Sunday morning I arrived at a small park next to a canal near Miami and found JetLev test pilot Stephen J. Grey and two of his colleagues waiting for me. The jetpack hung in a bright yellow steel frame. After performing some demonstration flights, Grey returned the machine to its frame and helped me strap in.

The JetLev is not quite the free-flying machine we all assumed we'd have by now. (In fact, it's technically not an aircraft but a boat, registered with the Coast Guard rather than the FAA.) Instead of hot gases, the machine shoots water from its nozzles, yielding an equal-and-opposite reaction to keep the user airborne. It's like riding around on a pair of fire hoses. The water comes via a 33-foot-long, 4-inch-diameter flexible hose connected to a modified personal watercraft. A 225-hp motor at the far end of the hose sends water up to the backpack and out to the nozzles at 1,000 gallons per minute. The JetLev can wander hither and yon for hours at a time, pulling its pump behind at speeds of up to 24 mph.

The JetLev's controls are simple: A pair of arms project forward from the backpack at shoulder height. At the end of each is a handgrip, with which the user can pivot the arm up and down. The nozzles where the water blasts out are attached to the other end of the arm, behind your shoulders. By moving the handgrip down, you angle the thrust forward; by moving it up, you angle the thrust downward. Move one handle up and the other down and you turn. The right-hand grip rotates like a motorcycle accelerator to modulate the overall thrust.

I waded out into the canal to begin the training. For my first attempts, Grey controlled the strength of the jet thrust via remote control, to keep my workload down. As we began, I was lying with my chest down in the water, face forward and with my arms stretched up over my head. Grey started the engine and gradually throttled up. My chest rose above the water, then my hips. Once I got the hang of balancing myself, he powered up further, until I straightened to an upright position and was floating above the water. I did some figure-8 turns, and in less than five minutes was comfortable enough with the controls that Grey handed over the throttle to me. The sensation of floating on roaring columns of water is exhilarating and surprisingly intuitive.

Because of the tether, a JetLev pilot can ascend to no more than about 25 feet above ground. That may not sound like much, but think of it as standing on the roof of a two-story house—it's a surprisingly intimidating height. I probably got no higher than 5 feet and was already feeling acrophobic, since, with my beginner-level skills, I felt like I might wobble out of control at any point.

The JetLev is so simple in execution that it's a little surprising to learn it took inventor Ray Li six years to bring the concept this far. The essential challenge, Li says, was the same as with any hovering craft: to prevent the propulsion forces from overwhelming the control forces. The JetLev can generate more than 500 pounds of thrust, yet the operator only needs to lean slightly to one direction to begin a turn. This disproportion is the main reason that a rocket belt takes many months of training to master. "If you have a fraction of a second delay in the response, you've already lost it," Li told me.

Li discovered that the JetLev's tether could operate as a sort of keel, making control a little easier. "I realized that I could use the weight of the water to my advantage," he said. "It lowers the center of gravity and greatly increases stability." As a result, an average schmuck like me can be hovering around within minutes. That means that resorts, for instance, could offer JetLev flights to ordinary customers after a brief training session. The sensation of flying is available with no more instruction than you'd need to operate a motorboat.

While I rested between turns, Grey and another experienced JetLev pilot, Keith Paul, took turns putting the machine through its paces, hovering and diving and engaging in maneuvers like the "submarine," which involves shooting under the water like a torpedo and then popping up in a rapid climb. To demonstrate what would happen in the event of a power failure, Stephen climbed to maximum height and then cut the power. He fell into the canal like a cannonball and came up grinning, equipment intact.

JetLev must be used close enough to the water that the trailing boat can suck up water to feed into the jetpack, though Grey and company have done land takeoffs from docks and piers. JetLev buyers will receive a day of basic training similar to what I experienced, and Li is also planning to set up academies that will train students to be JetLev instructors over the course of at least three days.

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