A jet pack, rocket belt, or rocket pack is a device worn on the back which uses jets of gas or liquid to propel the wearer through the air. The concept has been present in science fiction for almost a century and became widespread in the 1960s. Real jet packs have been developed using a variety of mechanisms, but their uses are much more limited than their fictional counterparts.
About Jet pack in brief
A jet pack, rocket belt, or rocket pack is a device worn on the back which uses jets of gas or liquid to propel the wearer through the air. The concept has been present in science fiction for almost a century and became widespread in the 1960s. Real jet packs have been developed using a variety of mechanisms, but their uses are much more limited than their fictional counterparts because of the challenges of the Earth’s atmosphere, gravity, the low energy density of utilisable fuels, and the human body not being suited to flight. The first pack design was developed in 1919 by the Russian inventor Alexander F. Andreev. A practical use for the jet pack has been in extra-vehicular activities for astronauts due to the apparent weightlessness and lack of friction-creating atmosphere in orbit. The term jet suit is used for a system incorporating a jet pack and associated jets attached to the arms to increase manoeuvrability. In 1962 Justin Capră claimed that he invented a flying rucksack in Romania, without arousing any apparent interest, but it is now displayed in a museum where it’s kept safe. In 1958 Garry Burdett and Alexander Bohr created a Jump Belt which they named after the jump at the 1984 Summer Olympic Games in Los Angeles, USA. After leaning forward, it was possible to run at a height of 7m with the belt’s thrust to aid the wearer’s jump. The wearer of the belt could then jump vertically with the thrust from the belt to aid his jump to 7m. The rocket belt could also be used to help the wearer jump vertically at a distance of up to 10m, making it possible for the wearer to jump at 7m at a time.
In contrast to, for example, turbojet engines, which mainly expel atmospheric air to produce thrust, rocket packs are far simpler to build than devices using turbojets. The classical rocket pack construction of Wendell Moore can be made under workshop conditions, given good engineering training and a high level of tool-making craftsmanship. The great disadvantage is the limited operating time. Currently, such rocket belts can only fly for about 30 seconds. A more conventional bipropellant could more than double the specific impulse. However, although the exhaust gases from the peroxide-based engine are very hot, they are still significantly cooler than those generated by alternative propellants. The main disadvantages of this type of rocket pack are: These circumstances limit the sphere of the application of rocket packs to very spectacular public demonstration flights, i.e., stunts; for example,. a flight was arranged in the course of the opening ceremony of the 1984 Olympic Games. The jet of steam and oxygen can provide significant thrust from fairly lightweight rockets, but the jet has a relatively low exhaust velocity and hence a poor Specific Impulse Velocity (SPV) The main disadvantage of a rocket pack, however, is that it can only provide a few minutes of sustained flight, rather than the sustained flight envisaged in sci-fi.