from the Curator's Office:
original Bell Rocket Belt in testing.
Ever Happened to the Rocket Belt?
My father didn't get a lot of magazines when I was
a kid. One he did get, however, was Popular Science. I
used to love grabbing them (when Dad was done reading them) to
see what new fantastic item - rocket ship, flying saucer, personal
submarine - was on the cover. All these inventions seemed to be
due to arrive in the year 2000, more or less. Some of my favorite
contraptions that often appeared on the cover were personal flying
devices: things like rocket belts, jet packs and miniature one-man
helicopters. Once these things were perfected by the beginning
of the 21st century, everybody, including me, would be able to
fly like Superman (or superwoman). Well, the 20th century is here
and these devices are still a dream. Whatever happened to the
I started looking around on the internet and found
that rocket belts have been a staple of pulp science-fiction since
the 1920's. Buck Rogers used a rocket belt. The movie serial King
of the Rocketmen brought the idea to the silver screen in
1949. Probably the first serious attempt to actually build such
a device can be credited to the Germans. During World War II there
was an effort to strap two primitive pulse jet engines - one on
front and one on back - to a dummy to see if a man could be made
to fly. The idea was that it would be valuable for soldiers to
be able to jump over mine fields, transverse rivers or fly up
cliffs. Nothing much came of the device and after the war it wound
up in the hands of American contractor Bell Aerosystems for a
close examination by engineers. Nobody was fool enough to attempt
to fly the thing, but a test with a tethered mannequin was run.
The device didn't prove practical, but the idea
must have stuck in the head of some of the Bell engineers. One
of them, Wendell F. Moore, started designing a single-man flying
machine for the Department of Defense. Moore realized that jets
engines were just too bulky and too complicated at this point
in their development to mount on a backpack. Instead he decided
to use rockets. This would be a simpler design and give the device
a better thrust-to-weight ratio -- in other words, for the same
amount of weight a rocket could give more lift than a jet.
The rocket fuel Moore chose was hydrogen peroxide
- yep, the same stuff in your bathroom cabinet that can give your
hair a bad dye job -- though at a much higher concentration. If
this doesn't sound particularly high-tech, well, there were other
rocket fuels that could have been used giving Moore three times
the power, but they tended to be unstable and dangerous to work
with. Given that the intention was to have somebody strap this
thing on their back, a less-hazardous fuel seemed prudent.
Not that hydrogen peroxide doesn't have a good kick.
When a high concentration of the stuff is passed through a metal
catalyst it breaks down into steam and oxygen. The steam takes
up a lot more space than the original components of the hydrogen
peroxide, so it goes shooting out of the rocket with quite a bit
The backpack was composed of three tanks. The center
one was filled with pressurized nitrogen and connected to the
outer ones which were filled with the hydrogen peroxide. When
the time came to launch the nitrogen flowed out into the outer
tanks and pushed the peroxide out two pipes that met in a Y just
above the chamber containing the catalyst at the top of the pack.
From that chamber the flow, now changed to high pressure steam,
was split into two pipes pointed downward with nozzles located
just behind the pilot's shoulders. The device was designed to
create 280 pounds of thrust which was enough to lift its own weight,
plus that of the pilot.
The design of the motor was relatively simple, but
building a way to control the belt so it could be flown safely,
was more difficult. Moore originally piloted the device himself
until an accident during testing broke his kneecap. Eventually
an elegant control system was developed that allowed the pack
and the nozzles to be swivelled to change the direction of the
thrust so the pilot, using a set of hand controls, could manuver
the belt up, down, foreward, back and even around in a spinning
motion. Later pilots reported that the belt was very easy to control,
but that they did need the protection of a thermal suit so that
the steam outflow would not burn their legs.
rocket belt creates thrust by using pressurized nitrogen
to push hydrogen peroxide into a chamber where thin silver
plates break it down into heat, oxygen and water. The water
is so hot it turns to steam and goes shooting out the belt's
nozzles at supersonic speed giving thrust
(Copyright Lee Krystek, 2007).
The problem with the rocket belt was range. The
rocket engine gave a lot of power, but not for very long. The
maximum flight was only 21 seconds. This made for great demonstrations,
but was of little practical value. Consequently the Bell rocket
belt became mostly a novelty, showing up in places like movies
(Thunderball), TV (Lost in Space) and special events
( the opening of the Olympics in 1984). Mainly because of the
flight time limitation, the military lost interest in the rocketbelt
in the mid-60's, but Moore had another idea. Jet technology had
advanced a lot in the past decade. Perhaps it was time to go back
and try a jet engine.
In 1969 Wendell Moore and John K. Hulbert of Bell
Aerosystems had Williams Research Corporation design a turbojet
small enough to be carried on a man's back. The jet was mounted
with the intake facing the ground and the exhaust shooting upward
to a pipe that split the outflow and pointed back down. Two nozzles
were located just in back of the pilot's shoulders similar to
those on the rocket belt. The jet had less power for its weight
than the rocket engine, but also used much less fuel. Tests were
carried out that showed that the pack could carry a man in the
air for ten minutes, and with improvements the flight time might
reach as long as a half hour (This device turns out to be the
one I'd actually seen on the cover of Popular Science).
The jet pack seemed to solve the biggest problem associated with
the rocket belt: range. Twenty-one seconds was now thirty minutes.
So why, if you parden the pun, didn't the jet pack take off?
As before, the military was the primary market for
the jet pack. As much as the length of flight had been improved,
it still fell short of their needs. Also, the change from a rocket
to a jet made the device much more complicated, difficult to service
and less reliable. A large support team would be needed to keep
thing running. Why commit that many people to keep a device in
flight that would carry a single man when you could employ them
to support a helicopter that could carry ten people?
Moore Jet Pack as it was featured on the cover of Popular
The commercial market for the jet belt also was
limited. Not only was the short flight time an issue, but there
was a question of safety. If the jet pack's engine failed - which
was not unlikely given the complicated design - there was no chance
of the pilot gliding to safety as he might in a helicopter or
an airplane. The fall would most likely be fatal, and with some
jet fuel still on board, perhaps even explosive. The jet pack
had a parachute system built into it but it wasn't very useful
if the machine failed below a height of about 70 feet.
Perhaps these problems might have been solved, but
in May of 1969 Wendell Moore died of complications from a heart
attack. Without his influence, the project was shelved and the
single jet pack sold to Williams Research Corporation where it
now sits in the company museum.
Over the years other people have tried to build
other personal flying machines. In 1995 a group of three men improved
on Moore's original rocket belt design by using newer, lighter-weight
materials. With less weight tied up in the mechanism, the device
could carry more fuel, giving it a longer flight time of 30 seconds.
They named the device the RB2000 Rocket Belt, and it might
have become popular for stunts (It is estimated the owners could
have earned $500,000 a year from the thing just in rentals.),
but shortly after a test flight the device disappeared. One owner
sued the others for its return. In an ugly turn of events, before
the lawsuit was settled, one of the men was beaten to death. The
location of the belt is still unknown.
So will my dream of flying a rocket pack ever come
to pass? Even if the flight only lasted 21 seconds it would be
a real thrill. Well, there still might be a chance if inventor
Ky Michaelson has his way. Michaelson has been building rockets
since 1951 (he bills himself as the Rocketman). I saw on
the internet that Michaelson was engaged in a project to build
a low-cost rocket belt that anybody could put together as a kit.
Now, I was a bit suspicious, as there are dozens
of inventors on the internet willing to sell you plans for stuff
that really doesn't have much chance of actually working. A perfect
example of this was seen on Discovery Channel's Mythbusters.
(For those who haven't viewed this show, the co-hosts, Adam Savage
and Jamie Hyneman, test the veracity of myths mostly by building
various things and then blowing them up or otherwise demolishing
them. Needless to say, the show is a big favorite here at the
museum.) Episode 32 featured them getting plans for a personal
flying machine off the internet for less than $100. The device
they built used a pair of ducted fans powered by a small gasoline
engine rather than a true jet engine. Despite spending ten-thousand
dollars on the project, however, they were never able to get the
rather impressive looking machine off the ground.
If anybody is able to build a working rocket belt
on a shoestring, however, it would be Ky Michaelson. Michaelson
holds 72 State National and International speed records for rockets
and founded C.S.X.T. (The Civilian Space Exploration Team) - the
first group of amateurs to put a rocket into space. I contacted
him by email and asked him how he decided to embark on this project.
"I saw some information on the internet that said
rocket belts cost $250,000 to build," he told me, "So I decided
to prove that you could build a rocket belt for the cost of a
motorcycle." Michaelson is pretty confident that he can make it
work. "Hydrogen peroxide rocket motors are pretty simple. The
problem is the control valve. That is the heart and the key to
a successful flight. I was lucky to obtain a complete set of prints
for the valve." If he can get it to work, he would like to see
plans published so that anybody could give it a try. "If I can
figure out how not to get sued, I will sell a kit," he told me.
So, maybe I'll get a personal flying machine after
all. I'll just save my money and avoid spending it on that new
Harley. A rocket belt ought to be safer, anyway, right?
Copyright Lee Krystek 2007.
All Rights Reserved.