Jet backpack

> What is the smallest jet engine that has been built and what is its
> power?  Can the engines be mounted onto a backpack with fuel and
> controls?  I have a rough sketch of how it is to be done but I would
> like to know if it is practical and whether it will work.  

Not only will it work, but Bell Aircraft already did it decades ago.  
(Bell also built the famous "rocket belt" AKA "jet pack" occasionally seen
in 1960's TV and movies.)  The Bell "jet belt" is only slightly more
practical than the Bell "rocket belt" was --- it took several minutes 
to run out of fuel, instead of a mere half-minute or so. However, the
specific fuel consumption of a jet engine is still too high to lift 
its own weight plus a pilot plus fuel for any significant length of time. 
To get the fuel consumption rate down to reasonable values requires
moving much larger masses of air at lower velocities --- i.e., some sort 
of rotor. A pure jet simply consumes too much power for a given amount 
of thrust. (NOTE: This is also one of the reasons why airlines switched
from pure turbojets to high-bypass turbofans.)


-- Gordon D. Pusch