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Jet pack

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For the band, see Jetpack (musician).
For the game, see Jetpack (computer game).
File:Bell Rocket Belt in flight.gif
The Bell Rocket Belt in flight.

Rocket belt, rocket pack, jet pack, and similar names, are various types of device, usually worn on the back, that use jets of escaping gases to allow the user to fly. The concept of these devices evolved from the 1920s when Buck Rogers, science fiction comic strip hero, used a rocket pack for travel.

The backpack harness (like a parachute harness), has a strap between the legs so that the pilot does not fall out of the harness during flight.

Types

The jet of gas in the original Bell Rocketbelt was provided by a hydrogen peroxide powered rocket but the jet can also be provided by a turbojet engine, a ducted fan, or other kinds of rockets powered by solid fuel, liquid fuel or compressed gas (usually nitrogen).

A similar device that uses rotors or propellers is a Backpack helicopter.

Hydrogen peroxide powered rocket

A hydrogen peroxide powered motor is based on the decomposition reaction of hydrogen peroxide. Nearly pure (90% in the Bell Rocket Belt) hydrogen peroxide is used: it is a colorless liquid with a density of 1.35 g/cm³. Pure hydrogen peroxide is relatively stable, but in contact with the catalyst (for example, silver) it decomposes into a mixture of superheated steam and oxygen in less than 1/10 millisecond increasing in volume 5000 times: 2 H2O2 = 2 H2O + O2. The reaction is exothermic, i.e. with liberation of much heat (about 2500 kJ/kg), forming in this case a steam-gas mixture at 740 °C. While very hot it is much cooler than other propellants reducing the risk of a fire.

This hot gas is led to one or more jet nozzles. The great disadvantage is the limited amount of fuel that can be carried. Because the jet of steam is what provides the thrust, the engine has a low specific impulse. The rocket belt not only uses the peroxide as fuel, but also as reaction mass — in contrast to, for example, jet engines which mainly expel atmospheric air to produce thrust. A man's carrying capacity sets an upper bound on weight, and so currently such rocket belts can only fly for about 30 seconds.

Rocket packs are simpler to build than devices using turbojets. The classical rocket pack of the construction of Wendell Moore can be prepared in workshop conditions but needs good engineering training and high level of tool-making craftsmanship. A main fault in the rocket pack is short duration of flight (to 30 seconds) and the high expense of scarce fuel (hydrogen peroxide). These circumstances limit the sphere of the application of rocket packs to very spectacular public demonstration flights. Rocket pack flights typically seize the attention of spectators and enjoy great success. For example, a flight was arranged in the course of the opening ceremony of the summer Olympic Games 1984 in Los Angeles, USA.

The German Jetpack of World War II

During World War II, Germany made late-war experiments of strapping two wearable shortened Schmidt pulse jet tubes of low thrust to the body of a pilot. The working principle was the same as the Schmidt-Argus pulse jet that powered the Fieseler Fi 103 flying bomb whereas the size was much smaller.

The device was called "Himmelstürmer" (Skystormer) and operated as follows: when the flier ignited both engines simultaneously the tubes began to pulse modulate. The angled rear tube strapped to the flier's back provided both lift and forward thrust while the chest mounted deflector tube of lower thrust maintained a constant upward thrust. This lifted the flier up and forward. By opening the throttle to the rear tube, calculated "jumps" could be made of up to 60 meter (180 ft) at low altitude (under 50 ft, 15 m). The tubes consumed very little fuel but not much could be carried either.

The intended use for this device was for German pioneers to cross minefields, barbed wire obstacles, and bridgeless waters. The device was never intended for troop use, despite a crude depiction of it in that role in the comic book and film The Rocketeer (which was a prop bearing no resemblance to the real device).

At the end of the war this device was handed over to Bell which tested it on a tether out of fear of harm as no test flier was willing to risk his life with the German machine. What became of the device is not known but Bell later came up with its famous "Rocketbelt" design that Wendel Moore claimed was his own. Although of different configuration and operation, it is suspected that Moore had knowledge of the German machine - hardly an "original" idea.

The fictional device used by The Rocketeer was a rocket pack that was technically unique (at least in the film adaptation) because it was designed to remain cool. The Himmelsturmer, by comparison, never operated long enough to get extremely hot and both tubes were angled away from the body of the flier. In operation the thrust difference between pulse tubes acted as a push/pull/lift system. Flight time for jumps was in seconds with no lengthy descent time as altitude was minimal. As soon as the throttle was disengaged the device was shut off, a very simple operation and no report of any casualties.

"German Secret Weapons and Wonder Weapons of World War II", Christof Friedrich, Samisdat Publications, 1976

Turbojets

Packs with the turbojet engine work on the traditional kerosene. They have higher efficiency, greater height and duration of flight, but they are complex in construction and very expensive. Only one working model of this pack was made; it underwent flight tests in the 1960s and at present it no longer flies.

Practical Applications

While jetpacks may seem appealing, real jetpacks made with current technology have little practical value. The United States military, which conducted most jet pack research, has declared that helicopters are far more practical. Many others have worked on devising a functional jet pack, but with limited success. Currently the most advanced designs are more similar to helicopters than jets. Because of the current impracticality of long-term use of jet or rocket packs, they have found more use in contemporary fiction or more futuristic science fiction.

History

The Jump Belt (mostly compressed gas powered)

(IMAGE: "jump belt" in action.)
In 1958 Garry Burdett and Alexander Bohr, engineers of Thiokol Corporation created the "Jump Belt", which they named Project Grasshopper. Thrust was created by high-pressure compressed nitrogen. On the "belt" were fixed two small nozzles, directed vertically downward. The "belt"'s wearer could open a valve, letting out from the nitrogen gas cylinder through the nozzles, in this case it was tossed upward to the height to 7 meters. After leaning forward, it was possible with the aid of the "jump belt"'s thrust to run at 45 to 50 km/h. Then Burdett and Bohr tested a hydrogen peroxide powered version. The "jump belt" was demonstrated by a serviceman in action, but there was no financing, and the matter again did not go to further tests.

The small size of the canisters is likely the reason why the name usage "-belt" rather than "-pack" became customary in the USA.

Aeropack

In 1959 Aerojet General Corporation won a U.S. Army contract to make a jetpack or rocketpack. At the start of 1960 Richard Peoples made his first tethered flight with his Aeropack.

Jet-Pack

A Swiss daredevil- Yves Rossy developed and built a winged pack with four engines under the wings, and can achieve true flight with it. He uses his body and a hand throttle to manuever.Rossy says he has become "the first person to gain altitude and maintain a stable, horizontal flight thanks to aerodynamic carbon foldable wings." Web-site w/ video

Development continues

But American servicemen did not lose interest in this type of flight vehicle. Control of transport studies of the U.S. Army Transportation Research Command, TRECOM) assumed that personal jet apparatuses could find the most diverse uses: for reconnaissance, crossing rivers, amphibious landing, access to steep mountain slopes, overcoming minefields, tactical maneuvering, etc. The concept was named Small Rocket Lift Device, SRLD.

Within the framework of this concept the administration in 1959 concluded with the company Aerojet General a contract to research on the possibility of designing an SRLD, suitable for army purposes. Aerojet came to the conclusion that the version with the engine running on hydrogen peroxide was most suitable. However, it soon became known to the military that engineer Wendell Moore of the company Bell Aerosystems had for several years been carrying out experiments to make a personal jet device. After becoming acquainted with his work, servicemen during August 1960 decided to send an order for Bell Aerosystems to develop an SLRD. Wendell Moore was appointed as the chief project engineer.

For later history, see below.

Official Rocketman website

The company which provides public Rocketbelt Performances

www.rocketman.org

Hydrogen peroxide powered rocketpacks

Bell Textron Rocket Belt

This is the best known type of jetpack or rocketpack. See Bell Rocket Belt.

RB2000 Rocket Belt

This is a successor to the Bell Rocket Belt. See Bell Rocket Belt#RB2000 Rocket Belt and http://www.canosoarus.com/07RocketBelt/Rocket02.htm.

Bell Pogo

The Bell Pogo was a small rocket-powered platform that 2 men could ride on. Its design used features from the Bell Rocket Belt. See this image.

Tecnologia Aeroespacial Mexicana (TAM)

The Tecaeromex Rocket Belt is said to be made by the only company in the world that offers a flying and tested rocket belt package, featured in the March 2006 issue of Popular Science magazine. Its maker claims that two of his rocketpacks first flew on 22 September 2005.

On Aug. 11, 2006 Isabel Lozano was the first woman in the world to fly in a rocket belt in front of millions of TV spectators, she flew with a special rocket belt built by TAM.

Turbojet pack (Bell Jet Flying Belt)

In 1965 Bell Aerosystems concluded a new contract with the Defense Advanced Research Projects Agency (DARPA) to develop a jet pack with a turbojet engine. This project was called the "Jet Flying Belt", or simply the "Jet Belt". Wendell Moore and John K. Hulbert, a specialist in gas turbines, worked to design a new turbojet pack. Williams Research Corporation (now Williams International) in Walled Lake, Michigan, designed and built a new turbojet engine to Bell's specifications in 1969. It was called the WR-19, with a rated thrust of 195 kgf (1,910 newtons) and weighing 31 kg.

The first free flight of the "Jet Belt" took place on 7 April 1969 at the Niagara Falls Municipal Airport. Pilot Robert Courter flew about 100 meters in a circle at an altitude of 7 meters, reaching a speed of 45 km/h. The following flights were longer, up to 5 minutes. Theoretically, this new pack could fly for 25 minutes and go up to 135 km/h.

For more information go to http://www.rocketbelt.nl/site.html and click on Bell Rocketbelt.
Also see http://www.rocketbelt.nl/html/people/Builders.htm for additional images. To book a Rocketbelt performance go to www.rocketman.org

In spite of successful tests, the U.S. Army lost interest. The pack was complex to maintain and too heavy. Landing with its weight on his back was hazardous to the pilot, and catastrophic loss of a turbine blade could have been lethal.

Thus, the "Bell Jet Flying Belt" remained an experimental model. On 29 May 1969, Wendell Moore died of complications from a heart attack he had suffered six months earlier, and work on the turbojet pack was ended. Bell sold the sole version of the "Bell pack", together with the patents and the technical documentation, to Williams Research Corporation. This pack is now in the Williams International company museum.

Special features of the turbojet pack

(See ru:Image:Jet Flying Belt.jpg Turbojet pack "Bell Jet Flying Belt". Pilot Robert Courter, 1969.)

The "Jet Belt" has a WR-1234 turbojet engine, which weighs 331 kg, thrust 1945 kgf (1,3910 N), diameter 30 cm. The engine is fixed vertically, with its air duct downward (1). Air intake is compressed by turbine and is divided into two flows. One flow goes into the combustion chamber. The second flow goes between the double walls of the engine, then it is mixed with the flow of the outgoing hot gases, cooling them and protecting the pilot from the high temperature. In the upper part of the engine the mixed flow is divided and enters two pipes, which lead to jet nozzles (2). The construction of the nozzles makes it possible to move the jet to any side. Kerosene fuel is in tanks (33) beside the engine. Control of the turbojet pack is similar to control of the rocket pack, but the pilot no can no longer tilt the entire engine. Maneuvering is carried out only by deflecting the controlled nozzles. By inclining levers, the pilot can move the jets of both nozzles forward, back, or sideways. The pilot rotates by the turning the left handle. The right handle, as usual, governs the engine thrust. The jet engine is started with the aid of a powder cartridge. While testing this starter, a mobile starter on a special cart was used. There are instruments to control the power of the engine, and a portable radio to connect and transmit telemetry data to ground-based engineers. On top of the pack is a standard auxiliary landing parachute (4); it is effective only when opened higher than 20 meters.

Real space use

Rocket packs can be useful in outer space, where much less thrust is needed, because the weightlessness of space removes the need to continually fight against gravity.

Rocket packs were tested during mission STS-64. Mission Specialists Carl Meade and Mark Lee tested the SAFER Rocket Pack while Hammond remained inside the Orbiter.

NASA's Manned Maneuvering Unit (MMU) (compressed gas powered)

In the 1980s, NASA demonstrated the Manned Maneuvering Unit (MMU), a rocket pack that allowed an astronaut to function as his/her own spacecraft, but the system was retired before the decade was gone. The MMU is the only jetpack of practical importance. Its operational area is outside a space station or spacecraft, where an astronaut can limitedly move independently. The MMU's propulsion was produced by high-pressure nitrogen gas discharged through nozzles (which the MMU has 24 of). The MMU was used since 1984 in three Space Shuttle missions (STS-41-B, STS-41-C and STS-51-A).

NASA's SAFER

Recently, NASA has introduced the SAFER, a smaller simpler version of the MMU meant to be used in case of accidental separation from spacecraft or station. With only small amounts of thrust needed, safety and temperature are much more manageable than in Earth gravity in the atmosphere.

Artist's depiction of a jetpack with folding wings

Jet pack or rocket pack with wings?

Jetpacks and rocketpacks would likely have much better flight time on a tankful of fuel if they had wings. There have been occasional real cases of a man gliding horizontally long distances with his body horizontal and no flying aid except airplane-type wings strapped directly to his body or clothing, wingsuits are a good example. On October 25th of 2005 in Lahti in Finland, Visa Parviainen jumped from a hot air balloon in a wingsuit with two small jet engines attach to his feet. The turbojets used provided approximately 16 kg (35 lbs) of thrust each and ran on Kerosene (JET A-1) fuel. Visa apparently achieved approximately 30 seconds of horizontal flight with no noticeable loss of altitude.[2]

Rocket pack in show business

In the 1960s the "Bell Rocket Belt" was on the peak of popularity. Bell arranged demonstration flights in the U.S. and other countries, each time causing the public enthusiasm.

In 1965 on the screens came the James Bond movie Thunderball. Bond (played by Sean Connery) penetrates an enclosed factory, where is concealed an agent of the mysterious organization SPECTRE. Bond liquidates the enemy, then flees to the roof and flies away using the previously hidden rocket pack.

In the filming two packs were used. One was a non-functional prop: it can be seen on Sean Connery in the large-scale planning scenes. The second was a genuine Bell Rocket Belt and it actually flew, piloted by Bell Company pilots Bill Suitor and Gordon Yaeger. The scenes with Sean Connery and the pack had to be shot twice, because the first time they photographed it his head was uncovered, and in the flying shots Bill Suitor flatly refused to take off without a crash helmet.

In the film's sound track the real shrill roar of the rocket pack's engine was replaced with the hiss of a fire extinguisher "to seem more realistic".

(IMAGE: Olympiad of 1984. Pilot Bill Suitor. Pack belongs to Nelson Tayler.)

One additional famous appearance of a pack occurred on the opening of the summer Olympic Games in Los Angeles in 1984. The pack was piloted by both Bill Suitor and Gordon Yaeger. Suitor, a legendary personality (in all calculation more than 1200 flights — more than in any other pilot to this day). Bill took off from platforms, flew above many spectators, who from the unexpected contingency covered their heads with their hands, and landed opposite the presidential platform, where sat Ronald Reagan. This flight was seen by 100,000 spectators on the platforms and about 2.5 billion television viewers (besides the USSR, which boycotted that Olympiad).

The company Powerhouse Productions Incorporated offers Rocketbelt performances around the world under the character name, "Rocketman". All together the "Rocketman" has performed over 1300 flight in 35+ counties for over 25 years. Such flights include, two Carnival Parades in Rio de Janiero, three Super Bowls, numerous TV shows and countless sporting events on every continent except Antarctica. Powerhouse Productions is the only company in the world providing "Rocketbelt" performances. Their website is www.rocketman.org Powerhouse Productions also owns the trademarks for "Rocketman" and "Rocketbelt"

In 2001 the Powerhouse Productions pilot Eric Scott stated that he had flown the jet pack to 152 feet (46 m) height. However, confirmation did not follow this record. There is however, video of the flight at www.rocketman.org showing the flight from the pilots point of view. The video shows an altimeter rising as the pilot rises higher.

The current and newest Powerhouse Productions pilot is "Rocketman" Dan Schlund.

Making a rocket pack at home using plans from the Internet

As depicted in Episode 32 of MythBusters, according to an urban legend, a jetpack or rocketpack may be affordably built from plans purchased off the Internet. The jetpack produced by the MythBusters was not powerful enough to lift itself off the ground, and was expensive to build.

Rocket packs in our time

In recent years the rocket pack has become popular among enthusiasts, who by their efforts have made some. The pack's construction is sufficiently simple, but suitability for flying depends on two key parts: the gas generator, and the thrust regulator valve. Specifically, they were led to the mind of Wendell Moore in the course of long tests.

The multiplication of packs is held in control by the scarcity of concentrated hydrogen peroxide, which is no longer produced by important chemical companies. Missileman-amateurs have made their own installations to make concentrated hydrogen peroxide by electrolysis.

In the world are now no more than 5 successfully flying rocket packs. For forty and more years from the day of the first flight of Harold Graham only eleven people (including him) have flown one, due to the lethal factor on the pack in free-air conditions (without the safety leash). Most known of them, as has already been mentioned, is Bill Suitor, who once lived near Wendell Moore and asked if he could fly with the pack, which Moore brought home in a baggage carrier.


Fictional use

Jet packs or rocket packs have been used in some movies, such as the 1965 James Bond movie Thunderball and the 1991 Disney movie The Rocketeer, and have long been a staple of science fiction in comic books and novels.

A number of variations of jet packs also exist, including rocket boots and "jump jets", which assist vehicles (usually mecha) or infantry in leaping across vast distances or over obstacles; examples of the latter include the powered armoured Space Marines from Warhammer 40K or the Mobile Infantry of Starship Troopers.

Stories

Video games

File:The Fury2.jpg
The Fury, a boss in Metal Gear Solid 3: Snake Eater, uses a jetpack for mobility.

Ratchet riding a jetpack from Clank.

See also

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