Editing Jet pack (section)

==Hydrogen peroxide–powered rocket packs==
A [[hydrogen peroxide]]–powered engine is based on the decomposition reaction of hydrogen peroxide. Nearly pure (90% in the Bell Rocket Belt) hydrogen peroxide is used. Pure hydrogen peroxide is relatively stable, but in contact with a [[catalyst]] (for example, [[silver]]) it decomposes into a mixture of [[superheated steam]] and [[oxygen]] in less than 1/10 [[millisecond]], increasing in volume 5,000 times: 2 H<sub>2</sub>O<sub>2</sub> → 2 H<sub>2</sub>O + O<sub>2</sub>. The reaction is [[exothermic]], i.e., accompanied by the liberation of much heat (about {{convert|2500|kJ/kg|abbr=on|disp=sqbr}}), forming in this case a steam-gas mixture at {{convert|740|C|F|disp=sqbr}}. This hot gas is used exclusively as the [[reaction mass]] and is fed directly to one or more jet nozzles.

The great disadvantage is the limited operating time. The jet of steam and oxygen can provide significant thrust from advanced rockets, but the jet has a relatively low exhaust velocity and hence a poor [[specific impulse]]. Currently, such rocket belts can only fly for about 30 seconds (because of the limited amount of fuel the user can carry unassisted).

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. Using a peroxide-based propellant greatly reduces the risk of a fire/explosion which would cause severe injury to the operator.

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 main disadvantages of this type of rocket pack are:
* Short duration of flight (a maximum of around 30 seconds).
* The high expense of the peroxide propellant.
* The inherent dangers of flying below minimum [[parachute]] altitude, and hence without any safety equipment to protect the operator if there is an accident or malfunction.
* Safely learning how to fly it, given that there are no dual-control training versions.
* The sheer difficulty of manually flying such a device.
These circumstances limit the sphere of the application of rocket packs to spectacular public demonstration flights, i.e., stunts; for example, a flight was arranged in the course of the opening ceremony of the [[1984 Summer Olympic Games]] in Los Angeles, USA.<ref>{{cite news
|title=Rocketman William Suitor recalls 1984 LA Olympics flight
|date=2012-07-29
|work=[[BBC News]]
|url=https://www.bbc.co.uk/news/av/magazine-19003777
|access-date=2020-10-03
}}</ref>

===Justin Capra's flying backpack===
[[Justin Capră]] claimed that he invented a "flying rucksack" (Romanian: ''rucsac zburator'') in 1956<ref>{{cite web|url=http://www.ctvnews.ca/sci-tech/romanian-who-claimed-to-invent-world-s-first-jetpack-dies-1.2197150 |title=Romanian who claimed to invent world's first jetpack dies |publisher=CTV News |date=20 January 2015 |access-date=20 January 2015}}</ref> in [[Romania]], and, without arousing any apparent interest, informed the American Embassy of his idea. However it was tested by Henri Coandă, a Paratrooper who crashed it the first time but managed the second after he advised to change the fuel and improve on the design. In 1962 a backpack was created at Bell Laboratories, following Justin Capră's prototype. The backpack is now displayed in a museum.<ref>{{Cite web |last=Alx |first=Dan Florian |date=2022-04-01 |title=Justin Capra and the flying backpack later used by NASA |url=https://www.electrokits.ro/en/justin-goat-and-the-flying-backpack-later-used-by-the-godmother/ |access-date=2023-04-22 |website=ELECTROKITS.RO |language=en |archive-date=2023-04-27 |archive-url=https://web.archive.org/web/20230427125958/https://www.electrokits.ro/en/justin-goat-and-the-flying-backpack-later-used-by-the-godmother/ |url-status=dead }}</ref>

===Jump Belt===
In 1958, Garry Burdett and Alexander Bohr, [[Thiokol]] Corporation engineers, created a Jump Belt which they named Project Grasshopper. Thrust was created by high-pressure compressed [[nitrogen]]. Two small nozzles were affixed to the belt and directed vertically downward. The wearer of the belt could open a valve, letting out nitrogen from the [[gas cylinder]] through the nozzles, which tossed him upward to a height of {{convert|7|m|ft|abbr=on}}. While leaning forward, it was possible with the aid of the jump belt's thrust to run at {{convert|45|to|50|km/h|mph|abbr=on}}. Later, Burdett and Bohr tested a [[hydrogen peroxide]]–powered version. The jump belt was demonstrated by a serviceman in action,<ref>{{cite web | url=https://www.theverge.com/2011/11/3/2504531/jetpack-history-future-passed | title=The Future Passed: Jetpack edition | date=3 November 2011 }}</ref><ref>{{cite news | url=https://www.newspapers.com/article/the-daily-times-rocket-powered-jump-belt/22962776/ | title=Rocket powered jump belt | newspaper=The Daily Times | date=24 June 1958 | page=9 }}</ref> but as no financing was forthcoming, there was no further testing.

===Aeropack===
In 1959 [[Aerojet|Aerojet General Corporation]] won a U.S. Army contract to devise a jet pack or rocket pack. At the start of 1960 Richard Peoples made his first tethered flight with his Aeropack.

===U.S. Army interest===
Transport studies of the U.S. Army Transportation Research Command (TRECOM) determined that personal jet devices could have diverse uses: for [[reconnaissance]], crossing rivers, amphibious landing, accessing steep mountain slopes, overcoming [[minefield]]s, tactical maneuvering, etc. The concept was named "Small Rocket Lift Device", SRLD.

Within the framework of this concept, the administration concluded a contract with the [[Aerojet|Aerojet General]] company in 1959 to research 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 F. Moore]] of the [[Bell Aerosystems]] company 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 commission Bell Aerosystems with developing an SRLD. Wendell Moore was appointed chief project engineer.

===Bell Textron Rocket Belt===
{{Main|Bell Rocket Belt}}
[[Image:Gene shoemaker with rocket belt.jpg|thumb|upright|[[astrogeology|Astrogeologist]] [[Eugene Merle Shoemaker|Gene Shoemaker]] wearing a Bell Rocket Belt while training astronauts]]

In 1960, the [[Bell Aircraft|Bell]] Rocketbelt was presented to the public. The jet of gas was provided by a [[hydrogen peroxide]]–powered rocket, but the jet could also be powered by a [[turbojet]] engine, a ducted fan, or other kinds of rockets powered by solid fuel, liquid fuel or compressed gas (usually [[nitrogen]]).

This is the oldest known type of jet pack or rocket pack. One [[Bell Rocket Belt]] is on display at the [[Smithsonian Institution]]'s [[National Air and Space Museum]] annex, the [[Steven F. Udvar-Hazy Center]], located near [[Dulles Airport]].

===RB-2000 Rocket Belt===
{{Main|Bell Rocket Belt#RB2000 Rocket Belt}}
This was a successor to the Bell Rocket Belt.<ref>{{cite web|url=http://www.canosoarus.com/07RocketBelt/Rocket02.htm|title=RB 2000|access-date=2005-07-08|archive-date=2016-04-02|archive-url=https://web.archive.org/web/20160402230335/http://www.canosoarus.com/07RocketBelt/Rocket02.htm|url-status=usurped}}</ref>

===Bell Pogo===
{{Main|Bell Pogo}}
The Bell Pogo was a small rocket-powered platform that two people could ride on. Its design used features from the Bell Rocket Belt.

===Powerhouse Productions Rocketbelt===
[[Image:Rose-4.jpg|thumb|upright|Rocketbelt pilot Dan Schlund at the 2007 Rose Parade]]
More commonly known as "The Rocketman", Powerhouse Productions, owned and operated by Kinnie Gibson, manufactures the 30-second flying Rocketbelt (June 1994) and organizes Rocketbelt performances. Since 1983 Powerhouse Productions has performed show flights in over 40 countries such as the Carnival in Rio de Janeiro, Super Bowls, the [[Rose Parade]], [[Daytona 500]], and the [[Michael Jackson]] [[Dangerous World Tour]], as well as many television shows including ''[[Walker, Texas Ranger]]'', ''[[The Fall Guy]]'' and ''[[NCIS (TV series)|NCIS]]''. Powerhouse Rocketbelt pilots include stuntman Kinnie Gibson and Dan Schlund.<ref>{{cite web |last=Spreadbury |first=William |title=Rocketman – Best exhibition Jetpack |url=http://www.rocketman.tv}}</ref>

===Jetpack International===
Jetpack International made three models of wingless jet packs. The company stated that the {{Proper name|Jet Pack H2O2}} could fly 152 meters, using [[hydrogen peroxide]] fuel for its rocket engine. It was flown for 34 seconds in [[Central Park]] on the 9 April 2007 episode of the ''[[Today (NBC program)|Today Show]]'' and sold for $150,000. Their H<sub>2</sub>O<sub>2</sub> jet pack was for demonstration only, not for sale, but the company stated that it could fly 457 meters, also with the hydrogen peroxide rocket engine.<ref>[http://www.jetpackinternational.com/equip.html JET P.I. – Jetpack International – Home of the Go Fast JetPack] {{webarchive|url=https://web.archive.org/web/20080730052216/http://www.jetpackinternational.com/equip.html|date=2008-07-30}}</ref> The T-73 was expected to fly up to 18 meters using [[Jet-A fuel]] and a jet engine, and to sell for $200,000.{{citation needed|date=April 2024}}

===Later technology===
At the [[TechCrunch Disrupt]] conference in 2014, [[Astro Teller]], head of [[Google X]] ([[Google]]'s research laboratory), said they investigated jet packs but found them too inefficient to be practical, with fuel consumption as high as {{convert|1/4|mpgus|L/100km|abbr=on|order=flip}}, and were as loud as a motorcycle, so they decided not to pursue developing them.<ref name="cnet.com">{{cite web|url=http://www.cnet.com/news/google-x-head-says-no-google-jetpacks-coming/|title=Google X head: Sorry, world, no Google jetpacks for you}}</ref><ref>{{cite news|url=https://www.forbes.com/sites/ericmack/2014/05/06/four-crazy-google-x-projects-that-failed/|title=Four Crazy Google X Projects That Failed | work=Forbes | first=Eric|last=Mack}}</ref>

In recent years, the rocket pack has become popular among enthusiasts, and some have built them for themselves. The pack's basic construction is rather simple, but its flying capability depends on two key parts: the gas generator, and the thrust control valve. The rocket packs being built today are largely based on the research and inventions of Wendell Moore at [[Bell Helicopter]].

One of the largest stumbling blocks that would-be rocket pack builders have faced is the difficulty of obtaining concentrated [[hydrogen peroxide]], which is no longer produced by many chemical companies. The few companies that produce high-concentration hydrogen peroxide only sell to large corporations or governments, forcing some amateurs and professionals to set up their own hydrogen peroxide distillation installations. High-concentration hydrogen peroxide for rocket belts was produced by Peroxide Propulsion (Gothenburg, Sweden) from 2004 to 2010,<ref>{{cite web |title=Peroxide Propulsion: Peroxide Propulsion |url=http://www.peroxidepropulsion.com}}</ref> but after a serious accident Peroxide Propulsion stopped making it.<ref name="cnet.com"/>{{Failed verification|date=September 2015}}