wrote:
Hello,
Has there ever been an actual rocket or jet prototype ever developed
that uses atomic Hydrogen? This is not necessairily a fuel cell, but
there is a lot of talk on how this could be 5 times as powerfull as a
conventional jet or rocket, & it seems fairly easy to produce, so has
this actually been tried?

I'm not sure what you mean by "atomic hydrogen".

If you mean monatomic hydrogen (just a single proton and electron
unbound to anything else), such a thing cannot exist at temperatures
short of a nuclear explosion of the inside of a star. It would
instantly recombine to form H2.

If you mean H2, then yes, it's done all the time for rockets. H2 is
what fuels the Space Shuttle main engines and fills most of the
external tank (along with Oxygen, O2). Both of these are kept liquid
a cryogenic temperatures.

H2 stored as a compressed gas has been played around with as a fuel
for vehicles of various kinds for decades. So far, it has proved
impractical for a variety of reasons.