J.B. Kalin
ID# 1695650343
WRIT 340
Dr. Ramsey
Mommy, I Want a Jetpack
Abstract: Since the 1920s, science fiction has proposed the jetpack as a futuristic technology.
After almost one hundred years and some moderate success, people today are left wondering if
the jetpack will ever be a reality. By exploring its origins and the recurring design flaws, one can
understand the jetpack’s slow development. The success of the Bell Rocket Belt captured the
world’s attention but eventually reached its limitations. Recent attempts to create a sustainable
jetpack have utilized various approaches, including a jet engine, water pressure, and ducted fans.
Each prototype’s accomplishments and failures are referenced in newspaper articles, scientific
journals, and engineering resources. The promise of the jetpack is ultimately overshadowed by
its continuous, predictable disappointment.
Keywords: aerospace engineering, mechanical engineering, physics, transportation, jetpack,
rocket, jet engine, personal flying machine, helicopter, Bell Rocket Belt, hydrogen peroxide,
jetman, Jetlev, Martin Jetpack, science fiction
Bio: J.B. Kalin is proud to be a native of Sioux City, Iowa. As an incoming junior in Viterbi, he
is majoring in Mechanical Engineering. J.B. currently serves as president of the Zeta Beta Tau
Fraternity where he was the first sophomore elected in chapter history. He enjoys playing
basketball, supporting USC football, and spending time with family and friends.
Multimedia Suggestion:
At the start of the section titled “Latest but not Greatest Attempts”, the following animation
could help illustrate how a jet engine works (as apposed to a rocket):
http://www.youtube.com/watch?v=MUxP3PCDRTE
If the YouTube clip is too long, the second animation on this site (“turbojet”) would also suffice:
http://www.animatedengines.com/jets.html
Kalin
Mommy, I Want a Jetpack
Introduction
It should be here by now. Our world is filled with advanced technologies like touch
screens, voice recognition, and holograms that were once just dreams within science
fiction. Man stepped foot on the moon over forty years ago. And yet, the jetpack has been
lost in the whirlwind of breakthrough technologies. Maybe its purpose is not as tangible as
the aforementioned, but if perfected, it could have numerous applications including the
military, transportation, and recreation. As inventors attempt to engineer personal flying
machines, the jetpack’s history resembles that of the airplane—but without the Wright
brothers. Despite some modest progress, nothing has embodied the sustained,
unrestricted flight comparable to Star Wars’ Boba Fett or Iron Man (see Figure 1).
Figure 1.
When we will have the
freedom to fly like super
heroes?
Military.com
A closer examination of the jetpack’s development reveals that it has long been
hindered by certain design challenges that still trouble engineers today. Even the most
elaborate, exclusive, and expensive models can't quite match the vision from science
fiction. Prototypes have emerged but none are available to the common man. We have yet
to see kids jetpacking around the neighborhood like it’s the coolest new toy. Its sputtering
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history and modern designs reveal why the true vision of the jetpack has never overcome
challenges of duration, cost, and mobility.
History
Not until a quarter through the 20th century did the
mere idea of a jetpack reach the public eye. In 1928, a
science fiction magazine called Amazing Stories published a
story about a veteran World War I pilot named Captain
Anthony Rogers. Known as “Buck”, the protagonist used a
compact jet engine on his back to fly around and fight crime
in the future. Buck Rogers quickly gained popularity and
eventually became a prominent comic series, television show,
and movie. By the 1930s, fiction was verging on reality when
Figure 2. The origin of
the jetpack can be
traced to Buck Rogers
Comics.org
a Russian man named A. Andreev patented an oxygen and methane-fueled flying device.
Complete with three-foot wings, a motor would be worn to produce enough power for
liftoff. Mark Wells, a research engineer who once worked for NASA and the US military,
called Andreev’s contraption “the first device of its kind that had any engineering detail at
all”. However, the design was never actually tested [1].
Also referred to as the “rocket pack”, “rocket belt”, or “jet vest”, the jetpack reached
a milestone in the late 1940s when engineers at a military base in Alabama began
researching rockets that could lift a person and allow him or her to land safely upright. In
1959, the US Army contracted Bell Aerosystems to create a “small rocket lift device” for
“light mobility systems missions”. The machine utilized motorcycle-type rotating grips for
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throttle and was powered by hydrogen peroxide. Eventually called the Bell Rocket Belt, its
breakthrough came in 1961 when pilot Harold Graham flew for thirteen seconds [2, 3].
During the mid-60s, the Bell Rocket Belt gained significant attention. Sean Connery
actually wore one in the successful James Bond film, Thunderball (1965) [3]. Some
organizations and individuals continued to spend time and money on its research,
including Bill Suitor who did stunt work as James Bond. Suitor eventually became known
for perhaps the most memorable jetpack flight in history, when he flew the rocket belt for
seventeen seconds inside the LA Coliseum at the opening ceremonies of the 1984 Olympics.
2.5 billion television viewers from around the globe watched him soar across the field. It
appeared that the jetpack had finally arrived, with the Bell Rocket Belt as the primary
design [1].
Early “Jet” Pack
It’s important to note that the Bell Rocket Belt, arguably the most famous jetpack in history,
is not actually a jetpack. Like its name suggests, the device utilizes rocket propulsion
instead of a jet engine. Bell Aerosystems also proposed a “Jet Belt”, but the Pentagon
turned it down because it was too heavy and bulky [2]. Thus the rocket approach was the
best available technology, and hydrogen peroxide proved to be the most economical fuel.
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Figure 3. Bell Rocket Belt and diagram depicting the hydrogen peroxide reaction
Smithsonian, MiracleGreat
The image on the left in Figure 3 looks futuristic and complex, but its functioning
principle is quite simple. The three tanks are standard on a Bell Rocket Belt. Labeled
number one in the diagram on the right, the center tank is filled with pressurized nitrogen
gas. The outside tanks (number two) are full of hydrogen peroxide. When triggered, the
nitrogen pushes the hydrogen peroxide through two pipes and into a chamber (number
three) filled with a catalyst, typically made of silver. This catalytic reaction violently
decomposes the hydrogen peroxide into superheated steam and oxygen. The hot, highpressure gas is split through a valve and shoots out two nozzles, generating a thrust with
gas velocity at about 1000 meters per second [4].
This technology dominated the world of jetpacks for over three decades, and some
inventors still use it today. Since the chemical reaction is so reliable, it allows engineers to
focus on meticulous issues like altering the sensitivity of the nozzles to balance thrust and
yaw. But despite the allure of hydrogen peroxide rockets, progress has literally and
figuratively hit a ceiling. Although it can “accelerate faster than a Formula 1 car”, the Bell
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Rocket Belt and its variations have yet to fly for over a minute. This is unlikely to change
because the additional weight of larger gas tanks negates the upward lift. And in over fifty
years of development, it is still difficult to fly and requires a lightweight pilot [5, 6]. With
these limitations and diminished funding, the rocket belt has been forced into obscurity.
Jetpack enthusiasts must have faith that innovation will save their dreams.
Latest but not Greatest Attempts
Following the Bell Rocket Belt, believers in the jetpack have pursued various techniques in
hopes of glory. Swiss daredevil Yves Rossy, nicknamed the “Jetman”, essentially
engineered a personal jet plane. It resembles something that a 12-year-old would doodle
in class: a concoction of homemade carbon wings attached to jet engines, which he straps
on his back. Rossy has been compared to the pioneers of flight in the early 20th century
who would risk death for success [7]. Any doubters were silenced last year, when he
dropped from a helicopter and flew 8,000 feet above the Grand Canyon at almost 200 miles
per hour [8]. Just based on the numbers, one quickly realizes that the jet engines are far
more powerful than their rocket counterpart. In a jet engine, a continuous charge of fuel
forces compressed air to expand through a turbine. This creates an explosion of gas out a
narrow opening at high speeds which provide the thrust [9].
Figure 4.
Yves Rossy’s
jetpack is powerful,
but heavy and
dangerous
Mech. Engineering Blog
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Rossy’s impressive flight may be the best real life reenactment of Iron Man, but it falls short
in other aspects. The engine-wing jetpack weighs about 120 pounds, and any slight
movement of the head, shoulders or arms will diverge its path [8]. Not only is it extremely
dangerous, his flight started from a helicopter, which defeats the very purpose of a jetpack.
Instead of a chemical reaction or jet fuel, the Jetlev R200 makes use of the world’s most
available resource: water. Created by Raymond Li and tested in 2009, the device looks like
a traditional jetpack with back strap, nozzles, and handlebars. Of course, this is excluding
the 33-foot-long hose connected to a floating vessel that contains a 255 horsepower engine.
When engaged, the motor pumps high-pressure water
up through the hose and out the nozzles of the pack. The
shooting streams of water create a reaction force that
propels the rider up to 28 feet in the air. The sensation
has been described as “a bit like riding around on a pair
of fire hoses” [3, 10].
Figure 5
Figure 5 illustrates the Jetlev’s operation and although it looks thrilling, it has not
solved the world’s jetpack problems. For instance, to actually own such a toy, it would run
you about $100,000. This is discouraging when considering its inability to reach ten yards
above the water, let alone the ground. The Jetlev is quite an engineering achievement but
cannot provide the freedom of flight essential to a jetpack.
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Similar to Yves Rossy creating a personal jet plane,
Glenn Martin has spent years designing a jetpack that is
virtually a personal helicopter. Martin and his team have
engineered a two-stroke gas engine that spins a pair of
ducted fans, generating enough thrust to lift a person
[11]. Because it is defined as a small vertical take-off and
Figure 6. Martin Jetpack in
flight.
Martin
lading aircraft (VTOL), Martin’s jetpack is not subject to
the same regulations as helicopters and fixed wing
aircraft. Nevertheless, the engineers have designed it to comply with the ultralight
standards of the Federal Aviation Administration, technically making it the safest jetpack
ever assembled [6]. In 2011, the jetpack flew for almost ten minutes and reached 3,500
feet. If it had been holding a live person instead of a dummy, Martin’s design would have
easily broken the record for longest flight (and highest discounting Rossy) [11].
The Martin Jetpack has many promising features, including a potential flight time of
thirty minutes and speed of sixty miles per hour. Granted this may be the best piece of
jetpack technology available today, it falls short in other respects. The Martin Jetpack joins
the Jetlev for a $100,000 price tag (keep in mind that Rossy’s design isn’t for sale). In
addition, a two-week training session is required before flight [11]. With a mediocre
control over lateral movement, this jetpack fails with the rest of its contemporaries.
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Disappointment
Besides the obvious flaws with the aforementioned models, there are some common
design challenges that must be overcome before the jetpack truly takes off. Considering the
record for longest manned flight is just minutes, engineers must find ways to extend its
duration. This poses a problem for rockets and jet engines since a limited amount of fuel
can fit on a person's back. Martin's fan-powered device may expend less fuel, but its large
size is a drawback. With a machine that huge, one might as well take a helicopter. Perhaps
the evolution of the jetpack will mock the computer and become smaller over time. Until
then, the noisy, short-lived, and oversized prototypes will keep the public at bay.
Another glaring setback with current jetpack technology is that it fails to truly
capture the desired freedom of movement. The Rocket Belt and Martin Jetpack lack the
ability to quickly accelerate in the horizontal direction; Rossy's jet wings cannot take off
and land vertically; and the Jetlev is permanently attached to a water hose. Nick Sagan (son
of famous scientist Carl Sagan), writes, "I think that's a shame because there's something
really exciting about the possibility of going wherever you want with your jet pack. It's the
ultimate expression of control over our dominion" [2].
The problem with increased mobility is that it often entails navigational issues. This
has plagued jetpack inventors since the original Bell Rocket Belt. Bill Suitor once compared
the act of flying like "trying to stand on a beach ball in a swimming pool" [5]. Furthermore,
most designs of today cite a weight limit for pilots (around 175 pounds) [2]. Factor in
safety issues due to midair malfunctions and burns from exhaust, and the concept of a
practical jetpack seems to fade away.
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Up until 2007, only seventeen people had ever flown a jetpack [5]. Granted the
recent inventions have surely increased that number, the future still looks bleak. Most
people can't help but have a feeling of getting “ripped off" [1]. But still, most would agree
"there is nothing that even comes close to the dream that the jetpack allows you to achieve"
[12]. Whether it utilizes a rocket, water, fan, or jet engine, the jetpack has remained
focused on giving an individual the freedom of flight. Its evolution has seen the creation of
some of the most innovative technologies of our day. But when things continually evolve,
they are supposed to produce a superior being. In the case of the jetpack, a revolutionary
design has eluded us. Its flight control, mobility, and sustainability issues have spoiled the
hopes of the population. Maybe some day we will be able to enjoy its capabilities, but until
then, it’s reserved for comic books, special agents, and the Jetsons.
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Sources
[1] M. Montandon, Jetpack Dreams. New York: Da Capo Press, 2008.
[2] L. Greenemeier, "The Trouble with Rocket Packs," Scientific American, Apr 29, 2008.
[3] J. Wise, "Jetpack at Last," Popular Mechanics, pp. 64, Dec 2011: Gale Cengage.
[4] E. Bengtsson. (2009, Sep 27). “How do Hydrogen Peroxide Rockets Work?”, Peroxide
Propulsion [Online]. Available: http://www.peroxidepropulsion.com
[5] D. Irvine. (2007, Feb 19). “Where’s My Jetpack?”, CNN [Online]. Available:
http://edition.cnn.com
[6] Unknown. (2012, Apr 17). “Personal Flying Jetpack Machine”, Mechanical Engineering
[Online]. Available: http://www.mechanicalengineeringblog.com
[7] G. Stewart, "Yves Rossy, the Swiss Adventurer," The Times, pp. 120, Nov 28, 2009. Gale
Cengage.
[8] "Jetman Over the Grand Canyon," Aviation History, vol. 22, no. 1, pp. 8, Sep 2011.
ProQuest.
[9] A. Sanghavi, "How Does a Jet Engine Work?," The Times of India, pp. 2, Dec 14, 1958.
ProQuest Historical Newspapers.
[10] "Jet Pack Takes Off," Current Science, vol. 95, no. 4, pp. 14, Oct 16, 2009. ProQuest.
[11] G. Mone, " Finally, the Jetpack Flies," Popular Science, vol. 279, no. 3, pp. 32, Sep 2011:
ProQuest.
[12] J. Schwartz, " From Comics to James Bond to a Liftoff in the Backyard," New York Times,
pp. A13, Jul 29, 2008. ProQuest Historical Newspapers.
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