Editing Jet pack (section)

==Overview==
In the most general terms, a jet pack is a wearable device which allows the user to fly by providing [[thrust]]. With the exception of use in a [[microgravity]] environment, this thrust must be upwards so as to overcome the force of gravity, and must be enough to overcome the weight of the user, the jet pack itself and its fuel. This necessarily requires the jet pack to continually push mass in a downwards direction.<ref name="whynot">{{cite news|last1=Burnett|first1=Dean|title=Jetpacks: here's why you don't have one {{!}} Dean Burnett|url=https://www.theguardian.com/science/brain-flapping/2014/sep/23/jetpacks-science-scientists|access-date=9 March 2018|work=the Guardian|date=23 September 2014|language=en}}</ref>

While some designs have power and/or mass supplied from an external, ground-based source, untethered flight requires all of a flight's fuel to be carried within the pack. This results in problems relating to the overall [[mass ratio]], which limits the maximum flight time to a few minutes, rather than the sustained flight envisaged in science fiction.<ref name="whynot"/>