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Thunderbolt Aerosystems Brings Rocketbelts to the Public
Nino Amarena is putting a new twist on rocketbelt technology: He's selling it to the public
Charles J. Murray, Senior Technical Editor -- Design News, September 28, 2009
Nino Amarena wants you to fly — not in an airplane, glider or helicopter. And not by flapping your arms.
No, Amarena wants you to strap a rocket engine to your back, ignite some hydrogen peroxide and shoot straight up amid plumes of superheated steam — like a miniature version of the space shuttle. He'll put a couple of handles on your rocket for steering. You'll be able to go up and down, side to side, forward and back. You'll be able to yaw while watching your feet dangle above the scenery below.
Admittedly, there are a few drawbacks. Amarena's rocketbelt will cost you $210,000 and the rides will be short — about 40 seconds each. There's also some danger. Wendell Moore, who invented the rocketbelt for Bell Aerosystems in the early 1960s, stopped flying after shattering his knee in a crash.
Amarena can guarantee, though, that your experience will be intense. "You have 133 decibels of noise and 400 pounds of thrust on your back," Amarena explains. "It makes your blood curdle. It's really scary the first time."
Still, Amarena wants to offer his product to those with a taste for, well ... adventure. He has sold four units to individuals in Russia, Spain, England and India. He has three more products in test.
And he wants to keep selling. He says he can think of two dozen applications for his 40-second, rocket-powered product. Ultimately, though, Amarena hopes to develop a jet-powered version with greater longevity - possibly up to four or five minutes. He foresees that version being used in firefighting, rescue and surveillance. He wants to sell it to municipalities for disaster operations.
"On 9/11, you would have needed less than a minute to bring a rope up to those people who were trapped," Amarena says with dead seriousness. "There's a long list of things you could do in less than 30 seconds."
From Obsession to Reality
For Amarena, building rocketbelts is a dream-come-true. Since childhood, he was enthralled with Hollywood depictions of jetpacks and rocketbelts in cartoons and movies. His enthusiasm for such devices goes all the way back to the old "Flash Gordon" series, he says.
Still, it was not until later that he realized his obsession could be a reality. In a meeting with veteran rocketbelt pilot William Suitor, he learned that the rocketbelt scene in the James Bond movie "Thunderball" was real. "When I saw "Thunderball," I thought the rocketbelt scene was a Hollywood trick — a stuntman on wires," Amarena recalls. "Then I met Bill Suitor, and he said he knew it wasn't a trick because he did the flying for that movie."
Amarena resolved then that he would build rocketbelts and sell them. "I decided if I built one and charged money to people for renting it, it would be a violation of the spirit of engineering," Amarena recalls. "I wanted to make it so it could be productized, so that anyone who had the money could own one."
To be sure, Amarena was aware of the numerous stumbling blocks of such a project. Rocketbelts burn 90 percent concentrated hydrogen peroxide, a fuel so volatile it is under the control of the U.S. Dept. of Homeland Security. Moreover, rocket engines gulp fuel at a rate of 2.2 lb per second, making it almost impossible to squeeze more than a minute of flight time from them.
"The trouble with rocketbelts is the flights don't last very long," says Chuck Eastlake, a professor of aerospace engineering at Embry-Riddle Aeronautical University. "The darn things just can't carry enough fuel to go very far."
Worse, the danger associated with rocketbelts is real. "With rocketbelts, you've got a few seconds of flight time and you're in the air without any backup," says Hal Graham, a pilot and engineer who served as the world's first "rocketeer," demonstrating rocketbelt technology for President Kennedy in 1961.
"Is it dangerous?" asks veteran rocketbelt pilot Suitor with obvious sarcasm. "If you consider you're strapping six gallons of 90 percent hydrogen peroxide under 600 psi to your body, flying any number of feet off the ground with the glide ratio of an anvil ... no, it's not dangerous."
Ready for Take-off
Amarena, however, is undeterred by engineering complexities and danger. That's why he has spent the last 12 years developing, testing and building rocketbelts as chief executive officer of his company, Thunderbolt Aerosystems. For Amarena, who earned his master's degree in electromechanical engineering at the Buenos Aires University of Engineering in Argentina, the complexities merely fuel his desire to build one-man rockets.
"From the beginning, I recognized that there were some drawbacks to using liquid propellants," he says. "But I still see it as a way to apply my knowledge and fulfill my childhood dream of building and flying a rocketbelt."
In his design, Amarena has followed the lead of rocketbelt pioneers from the 1960s. He employs a gas generator that uses a catalyst to decompose hydrogen peroxide, resulting in an exhaust gas mixture of superheated steam and oxygen. Amarena says each pound of hydrogen peroxide in the engine creates 61 ft3 of gas at the exhaust, generating the rocket's thrust.
To ensure the rocketbelt pushes gas out at sufficient pressure, Amarena stores the hydrogen peroxide in two pressurized stainless-steel cylinders that the rocketeer wears on his or her back. Each cylinder holds between 2.5 and 3 gallons of fuel. Above the liquid fuel, he injects an inert gas — usually nitrogen — at 400 psi. As a result, the pressurized nitrogen pushes down on the fuel in a classic "blow-down" arrangement. Amarena says his most significant use of off-the-shelf components is in the plumbing of the pressure regulation system. O-rings and JIC fittings come from Parker Hannifin Corp. Thunderbolt's first-generation rocketbelt also employed a Grove Mity Mite Model 94 pressure regulator, while second-generation systems uses a pressure regulator from Aqua Environment Co. Inc.
In essence, the role of the fuel storage and pressurization system is to feed the hydrogen peroxide to the rocket engine at high pressure. Fuel is forced from the tanks, down through a manifold that connects them to the rocket engine. There, fuel flow is dependent on the action of a throttle valve, controlled by the pilot's right hand. When the pilot cracks the throttle open, the liquid propellant changes to a gas, expanding in volume by a factor of about 5,000. Ultimately, it decomposes in a few milliseconds, then exits at 350-400 psi as superheated steam and oxygen at a temperature ranging from 1,000 to 1,750F.
"The amount of gas is so large that when it comes out of the nozzle, it gives you thrust, and therefore, lift," Amarena says.
Beyond Hovering
In all, the ThunderPack's rocket engine produces about 380 lb of thrust, enough to lift a 180-lb man, the rocketbelt itself, and up to 140 lb of fuel.
Once the pilot is aloft, however, he or she needs to be able to vector the exhaust nozzle to enable turning, as well as up-and-down movement. "The concept of a rocketbelt is pretty simple: You get a little more thrust than weight, and you go up," says veteran pilot Graham. "But the real trick is to get those thrust vectors so they're not completely random."
For that, Amarena designed a tube assembly with a gimbal at the base of the pilot's neck, about which the exhaust nozzles can rotate. The assembly, which also holds the fuel and nitrogen tanks, has control arms attached to it. To move forward, the pilot pushes down on the control arms, which point the nozzles backward. To move backward or to slow down, the pilot does the opposite: Pulling up on the control arms vectors the nozzles forward, essentially "putting the brake on."
By using so-called "jetavators," Amarena's rocketbelt can also mimic the behavior of an airplane's ailerons. The jetavators — essentially small rings mounted on the exit areas of the exhaust nozzles — are operated by an actuator at the pilot's left hand. By twisting the actuator to the left, the jetavator on the left nozzle moves downward while the one on the right moves upward, creating a push in one direction and allowing the pilot to yaw. By twisting the actuator to the right, the pilot can yaw in the opposite direction.
To simulate a plane's rudder, Amarena also enables the pilot to tilt the tube assembly about the gimbal. In essence, the pilot tilts his or her entire body, raising one arm while lowering the other. Doing that while operating the jetavator allows the pilot to do a banked turn.
"In order to turn, you need to simulate the action of both an aileron and a rudder," Amarena says. "By combining both those actions, you can make a banking turn."
Extending Flight Duration
Doing all that, however, still didn't enable Amarena's rocketbelt to exceed the performance of Wendell Moore's 1960s rocketbelts, which could fly no more than 21 seconds.
So Amarena took his design a step further. To extend the flight duration and make his product more desirable to potential customers, he launched a search of available literature for chemical formulas that would pack more punch than conventional hydrogen peroxide. Poring over more than 2,500 technical documents dating as far back as 1850, Amarena learned that he could combine decomposition enhancers, additives and promoters to boost the so-called "specific impulse." Thunderbolt Aerosystems named the proprietary mixture "Pertol" and applied for a patent on it.
To further enhance the flight duration, Amarena also changed two other aspects of the design: The new ThunderPack frames employ aerospace-quality materials; and the fuel tanks hold about twice as much fuel as the 1960s versions. In the tubular frame, Amarena used such materials and alloys as titanium, Inconel, Hastelloy and magnesium, as well as composite carbon fibers, graphite and Kevlar. By cutting the weight of the ThunderPack and doubling the fuel capacity, Amarena says his product can now fly 45 seconds at full throttle. Using Pertol-based fuel boosts the time to 75 seconds, he says.
Still, the flight duration is seen as an obstacle to broader interest. "We do get a lot of requests from people who might be able to pay the cost, but they're turned off by the short duration," Amarena says.
He adds, however, that Thunderbolt Aerosystems plans to eventually boost the duration of its products to as much as four or even five minutes. To accomplish that, Amarena has begun building small prototype units using jet engines instead of rockets. Working with a Czech company that makes small jet engines, he hopes to be able to develop full-size jetpacks within 12 to 18 months.
If the company can do it, Amarena says he believes he will have more customers. He already envisions the jetpacks being used for fire and rescue operations, as well as for military and surveillance applications. One potential customer claimed he could save millions of dollars per year in the laying of high-tension wires if he could replace helicopters with jetpacks, Amarena says.
Experts say that Amarena's dreams are a tall order, but not necessarily impossible. "Nearly every new technology has a list of detractors who say it can't be done," says Eastlake of Embry Riddle. "But new analysis tools, new fuels, new structural materials are always coming up. I'd be hard-pressed to say that anything's impossible."
"Some people have told me, ‘You could be the Henry Ford of rocketbelts,'" Amarena says with characteristic optimism. "I like that."
Watch Suitor's test of Amarena's rocketbelt here. Read more about rocketbelts here.
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Thunderbolt Aerosystems Brings Rocketbelts to the Public
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So, considering my 260lbs of manly bulk, I'd get as much flight time jumping off of the flatbed of my pickup truck. I feel very fat-conscious. I need to go to the snack machine...'>"In all, the ThunderPack's rocket engine produces about 380 lb of thrust, enough to lift a 180-lb man, the rocketbelt itself, and up to 140 lb of fuel."
So, considering my 260lbs of manly bulk, I'd get as much flight time jumping off of the flatbed of my pickup truck. I feel very fat-conscious. I need to go to the snack machine...
James M. Dinsmore - 2009-19-10 15:47:03 EDT -
Hopefully nobody flames this article too bad, but you don't ignite the hydrogen peroxide. The catalytic breakdown is mentioned in the article. Come on, as technical people we can do better than that. . .
PK - 2009-15-10 16:53:41 EDT
