We knew that the jetpack was an established form of art,  and that the work in hydro thrust sport that Stratospheric does is “standing on the shoulders of giants”. However it took the attack of a None Producing Entity (NPE) to realize exactly how tall the giant is. We and our researchers have now amassed an overwhelming amount of prior art with the majority of it coming from the aerospace programs of the U.S.  It makes us clearly aware of the tradition that we are carrying on and the continuum not only in the pursuit, but the tools and devices.

With no knowledge of history, or simply failing to acknowledge it, one could not be blamed for thinking that hose connected flight sport was invented sometime in the 2000’s.  Nothing could be further from the realities of history.  Man’s desire to fight the pull of gravity and fly has been a constant for centuries. Engineers and technicians spent millions of dollars and countless man-years working out systems to push pilots and machines off the ground using the thrust from compressed fluids.

Let’s start at the basics with a definition of some of the terms.  Obvious for the most part, but crystal clear for the non-native English readers.

  • Vector, a quantity having direction as well as magnitude, especially as determining the position of one point in space relative to another. [Vecteur, une quantité de direction, ainsi que présentant grandeur, en particulier en tant que détermination de la position d’un point dans l’espace par rapport à l’autre. ]
  • Thrust, the propulsive force of a jet or rocket engine. [Poussée, la force de propulsion d’un moteur à réaction ou fusée.]
  • Jet, a rapid stream of liquid or gas forced out of a small opening. [Jet, un flux rapide de liquide ou de gaz forcé sur une petite ouverture.]
  • Flight, the action or process of flying through the air. [Vol, l’action ou le processus de voler dans les airs.]
  • Tether, a rope, chain, or the like, by which a mobile object is fastened to a fixed object so as to limit its range of movement.  The term umbilical is also used. [Tether, une corde, une chaîne ou comme, par lequel un objet mobile est fixé à un objet fixe afin de limiter son amplitude de mouvement. Le terme est également utilisé ombilical.]

The mechanics of hydro flight are derived from aspects of aerospace technology, specifically the jet propulsion arena. The history of jet based propulsion goes back to seventh century fireworks, while jet based flight begins in the late 1930’s with the invention of the jet engine. The term “Jet Age” was coined in the 1940’s to describe the advancement that the jet brought in speeds and efficiency of propulsion.  The term “jet” includes liquid or solid fuel rockets as well as turbo engines.  They all produce thrust, force in one straight linear direction.   Push out mass at high speed out of one end and the container moves in the other direction.  Like lighting a bottle rocket, light it up and it goes in whatever direction it is aimed until the fuel runs out.  Good for limited use. Steering becomes an obvious necessity to control and harness the power. That is where vectoring comes in, steering the thrust, changing and controlling the direction of the thrust.  Jet aircraft mostly work by leveraging against the movement of the air with flaps and ailerons to induce changes in direction.  Rockets are more basic, vectoring, or steering, the actual thrust stream.

To raise something off the ground, the mechanics are simple, more force than mass, overcoming gravity.  This led to a simple set of factors to optimize, more thrust, less weight.  The research led to exploration in every direction to achieve these two goals.  Naturally, items that generate, or store energy are heavy, and the fuel itself is heavy.  If the object utilizing the thrust can be kept in the vicinity of the power generator or power storage, the two can be linked by a hose, conduit or tether.  The following tracks some of these explorations and realized flight systems over the years utilizing hoses to connect the heavier weight pumps or storage tanks to the mobile apparatus.

There are a lot of milestones in the timeline of vectored thrust flight leading up to hydro flight.  The whole field is called vectored thrust flight,  jets provide the thrust, vectoring is a way of saying “directing” and steering the thrust.  The exploration of the concept has been ongoing for at least half a century. Before there was a jetpack, there was a jetboard, first flown on February 2, 1951. Both devices flew connected to a firehose.

Here in short description are the steps along the way that only deal with the tethered, or hose connected pursuits.  Click on any of the titles to show the video where available and description. Each of these experiments is thoroughly covered in government issued documentation, some of which we have listed on other pages.

  1. The First Jetboard, Zimmerman’s NACA experiment standing a platform supported by a jet of air.
  2. Thomas Moore, hydrogen peroxide connected jetpack

    Thomas Moore worked for the US Army and in the early 1950’s experimented and patented a soldier mobility unit.  His initial testing was connected to a fluid supply hose and the back pack was contained in a test rig.

    Thomas Moore

  3. Wendell Moore, first firehose connected jetpack tests

    Wendell Moore who went on to develop the hydrogen peroxide powered jetpack, first tested the concept of lifting the pilot up under the shoulders with a compressed air connected jetpack.

  4. NASA Langley hose pressure supplied models outdoors

    These were first powered by pumped hydrogen peroxide that flashed into steam at the jet, later the method became simpler using only compressed air.

    Prior Art for Raymond Li and Frankie Zapata patents

  5. NASA Flying Platform Research

    Hybrid platform combining air jets and propellers for control and lift. Flexible air hose supplied from below the platform.

  6. NASA compressed air supply for jet simulation in wind tunnels

    In free flying wind tunnels, the power supplied to many of the models was compressed nitrogen gas supplied via flexible hose.

    wind tunnel diagram-crop

  7. NASA lunar lander simulator

    Flexible hose supplied compressed fluid propulsion and steering.

    Prior Art for Raymond Li and Frankie Zapata patents

  8. Jet Shoes

    Flexible hose to compressed air tank with foot angle vector control.

    Thrust Vectored Prior Art

  9. Gemini 10 Spacewalk, Hand Held Maneuvering Unit

    Gemini astronauts used a nitrogen gas powered hand held set of dual “tractor” thrusters and a single “push” thruster, hooked up to a long flexible compressed fluid supply hose going back to the base unit, the spacecraft.

    Gemini 1966 Tethered HHMU s66-17480

  10. Skylab Foot Controlled Maneuvering Unit

These are a sub set of a much greater group of individual propulsion devices based on vectoring the thrust from jets.  These are the direct ones, the ones that are connected to a flexible hose transferring thrust energy from a base unit to a mobile one.  By the time hydro sport had been synthesized, the pressurized hose supply was a convention, a common method that was used to supply thrust to lift devices.  All that detailed work that NACA, NASA and the US Army published about hose connected vectored thrust flight. This history is in documents called NPL, or Non Patent Literature. These are documents that are published that contain prior art. None, as in zero, of the documents above were presented, referenced or vetted in the patent examinations of Li and Zapata.   As inclusion into and examination process of the above fields of endeavour would have resulted in the rejections of the applications, the result is the USPTO issuing what is referred to as a “poor quality” patent.  A patent that will not stand up to further scrutiny. A patent where the claims can be disregarded as invalid.

We gratefully acknowledge the work done by the giants, government  and private engineers and inventors and technicians, our ancestors who wanted to fly just as bad as we do.  Stratospheric, as Li and Zapata, operate in a continuum of development of vectored thrust flight. While genuine innovation of sub components may be able to have patent protection, the overall concept of a jetboards, jetpacks, jetbikes cannot be owned or lorded over.  These are the culturally known knowns, transitioned or placed into the public domain.  The foundations built long ago, for some, the unknown knowns.

History has our backs, and it is the history written by giants.

The question of who invented the jetpack, jetboard, jetchair, pod-racer, footjets, hand jets?  Ultimately, who cares? Move forward and make good equipment, treat your customers right, listen to the users and evolve your gear.

Below are some of the highlights of the documents, practically speaking, there are so many documents and so many references that invalidate the patent barriers on the sport that we have exceeded our ability to catalog and describe them for the time being.  Now it is in the hands of our legal team and we will get back to concentrating on what we do best, making gear that get you in the air.

This is the cool one, the uber mack daddy document of the thrust vectored sport.  NACA Research Memorandum, RM L52D10,  “Preliminary Experimental Investigation of the Flight of a Person Supported by a Jet Thrust Device Attached to His Feet”. Detailing Charley Zimmerman’s experiments with hooking up a firehose to a plywood board and kicking off (albiet slowly) the sport of vectored thrust flight.

Here is the first announcement in a publication to the world after it’s top secret classification was removed.  As the record shows, the “apparatus” was first tested on February 2, 1951, the Research Memorandum published two years later on January 15, 1953, then stamped as “Classified” and then made public in 1955.
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What is cool about this document is that toward the end it references further tests outdoors of the jet-platform.

Since reference 1 was published (1953) flights on a jet-supported platform were made out-of-doors. Figure 10 shows a typical flight on the jet-supported platform. The riders of such a vehicle had practically no difficulty with the wind. In calm air the rotor-supported vehicle hovers more steadily than the jet-supported vehicle. In gusty air the rotor supported vehicle was more disturbed.

“Typical flight”, far from being a mere experiment, in the three years since the first trial, the platform had become almost a method of testing jet concepts.

Notice in Figure 10 below that the platform size has shrunk to foot width and the support legs are compact and protect the jet from the ground, naturally.

The notes in this document referencing the jet-platform:


3. By comparison with a low-inertia jet-supported platform previously tested, the teetering-rotor-supported platform flew steadier in calm air and with larger oscillations in gusty air.

4. Although a substantial inertia of the machine did not appear to be particularly critical, an arrangement in which the flyer’s body moved with the flyer’s feet was physically easier to fly in rough air.

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NACA, which was the predecessor to NASA, the National Advisory Committee for Aeronautics ran from 1915 until 1958 when it transitioned into NASA with the dawn of the space age. These documents are important because they reinforce the first publication and availability to the public of the information. The prior art.


The grandfather document.

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Col. David Henderson testing the jetboard prototype in 1951

It is cold in February in a 6-8 knot wind with a hundred mile an hour air blast coming out under your feet.

There have been six occasions, over the last 172 years, when a decisive advance in man’s mastery of the air has been reported. Five of these have been reports of the free balloon, the directible balloon, the gliding airplane, the powered airplane and the helicopter. Today’s triumph is called thrust-vector flight.

True Magazine, December, 1956

Thrust vector flight.  Thrust vectored flight using a fluid for propulsion. Sounds like our sport of jetpack/jetboard hydro flight. The quote is from 1956.  Fifty eight years ago.  True magazine, “The best selling men’s magazine” December 1956.  We have a copy here in the Stratospheric office, it is great reading. Here is the backbone of the history as told in 1956, it goes like this..
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V-STOL Concepts and Developed Aircraft AFWALTR86-3071volume01-69

Bel Aerosystems started company-sponsored exploratory work on the concept, under Moore’s direction, in 1957 after becoming aware of the U.S. Army’s (TRECOM) interest in individual aerial mobility. A tethered system was used with pressurized nitrogen gas as the rocket propellant during the initial efforts.


June 16, 1958

Just 25 years after Buck Rogers first-streaked across the country’s comic pages propelled by his personal rocket belt, the thing has actually been invented by three young scientists in Denville, N.J. They call it a Jump Belt, which sounds as handy as an automatic clutch; but you don’t just run one through the loops in your trousers. You attach it to your body with “straps and belts and things,” according to Alexander H. Bohr and Harry Burdett Jr., two of its inventors, who are vague about details because they haven’t got them all patented yet. Then you blast off, and the thrust of the rocket on your back counteracts gravity so that you are virtually weightless. You can leap a river, spring lightly up a mountain or run like the wind. Pushed along by his rocket, one man was clocked at a speed which would have given him an under-two-minute mile if he hadn’t run out of fuel.

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This is the groundbreaking research, paid for by the US government and published more than fifty years ago that lead to numerous developments. The existence of these movies, images, reports keeps open the hydro sport field and prevents anyone from claiming ownership and attempting to establish a monopoly. The pilot seated in the chair is connected to hoses, has a center of gravity clearly below the thrust nozzles, and is most certainly mobile in relation to the base unit, tank or compressor.

  • a body unit having a center of gravity, wherein the body unit includes a thrust assembly having at least two thrust nozzles located above the center of gravity, the thrust nozzles being pivotally coupled to the body unit;

  • a delivery conduit in fluid communication with the thrust assembly; and

  • a base unit in fluid communication with the delivery conduit, the base unit capable of delivering pressurized fluid to the delivery conduit, wherein during operation the body unit is independently movable with respect to the base unit and capable of flight.

and for good measure:

  • a platform having a bottom surface, and a top surface on which a passenger can be positioned;

  • a thrust unit adapted to be supplied with a pressurized fluid, and including at least one nozzle engaging the bottom surface of the platform and oriented to provide thrust in a direction away from the position of a passenger on the top surface; and

  • a means for collecting and distributing pressurized fluid to the nozzle, the means for collecting and distributing pressurized fluid being configured to connect a supply channel to the propulsion device;

  • wherein the means for collecting and distributing pressurized fluid comprises a base to which said supply channel is connectable, said means for collecting and distributing pressurized fluid being attached to the platform in a manner that enables the base and a connected supply channel to move relative to the platform.


One of the more intriguing civilian markets being considered by the rocket industry is sports.

They also agree that the personal rockets, they call their’s the “AeroPAK” — will find wide use in rescue work, fire fighting, construction, transportation and sports.


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These images come from the NASA History website for work done at the Langley Research Center. The images, the work, everything is f’ing awesome. The amazing repository of tens of thousands of photos can be found here at the Langley History Section of NASA CGRIS website.  Above and beyond the sheer awesomeness of the photos is the direct lineage back to Charley Zimmerman’s first tethered experiments and the convention that fluid thrust flight had become by eleven years later in 1962.

This personal propulsion unit has a central jet in the middle of the platform and a plurality of nozzles that direct the motion and control.  But cutting out the patent language bullshit, this unit flies on pressurized fluid using the main nozzle for thrust and balances not using the motion of the body, (this was a model for a larger lunar lander that would eventually use jet to land on the moon) but using valved compressed air for directional and stabilizing controls. The four main verticals look like jets but are not, no flexible pressure hose tubing connecting. The extension tubing, looking to be about 17 mm diameter controls the yaw and roll.


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This is quite a gem of a report. At first blush it looks as though is is going in another direction, Zero G maneuvering belts.  Orbital space is cool, but not directly applicable to earthbound, aka one G flight, or so we thought.  This report actually extends the previous work, theory and proofs of tethered flight, center of gravity in relation to nozzles, and pivoting of the nozzles, all important components of our hydro flight sport.

The first man-lift device built by Bell was flown by several people (under controlled conditions) to determine the feasibility of the rocket belt concept. The rig incorporated two fixed rocket nozzles extending laterally from a shoulder harness, which under hovering conditions provide a thrust equal to the man-plus-rig weight. In the test rig, thrust was developed from high pressure nitrogen supplied from and external source through a flexible hose to the rocket nozzles. Figure 10 shows this test rig in action. Hovering flights of short duration were accomplished with some short fore, aft and lateral translations.

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V/STOL Concepts & Developed Aircraft, A Historic Report, Vol. 1  Wendell Moore flying the pressurized hose version of the first jetpack, 1957. Notice the Y split and the centering over the body side center line.  Support for lifting the body is padded loops under the arm pits, independently swiveling nozzles that have counterweight stabilization built in.

V-STOL Concepts and Developed Aircraft AFWALTR86-3071volume01-69


V-STOL Concepts and Developed Aircraft AFWALTR86-3071-Contrails-73

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