I've had an idea floating in my head recently and would love if someone more knowledgeable with physics or engineering could review it/debunk the idea.
There have been many ideas related to using balloons as launch platforms, but what about a small 'rocket' that utilizes the gas from a hydrogen balloon as a fuel to reach orbital velocity, once it's out of the dense atmosphere.
The idea, if at all viable, would only make sense for tiny payloads.
The main challenges in this idea seem to be:
Is there enough energy in the hydrogen gas to begin with?
Can you convert the gas into a liquid state quickly, in flight? What kind of mechanism could be used and what would be the minimum mass of it?
Would you need to carry up liquid oxidizer? I'm assuming a liquid-fuel rocket, but perhaps there are better options? (Something utilizing hydrogen, or maybe helium).
Is there a current technology that can use the hydrogen in it's gaseous form, combined with captured atmospheric oxygen, as a propulsion mechanism? (Avoiding the need for conversion all together).
So to those of you who understand the physics and engineering, is this possible -- or practical? Thanks!