On Fri, 28 Nov 2003 00:50:59 GMT, "johnhare"
wrote:

I do advocate some forms of air breathing propulsion for some
acceleration missions. I do not believe in hauling it all to orbit, or
increasing architectural complexity of the vehicles to the degree

I tried posting this on sci.space.tech, but it doesn't seem to have
gotten there... :-(

I was reading a textbook the other day ("Space Propulsion Analysis
and Design" - Humble, Henry & Larson, McGraw-Hill, 1995) Under the
topic of 'Advanced Propulsion Techniques', they described a rocket
motor that uses ram-air to augment the on-board oxidizer supply -
using some air to aid in burning a fuel-rich mixture.

Which got me to thinking - could it be turned around...? Add a
supplementary oxidizer to current turbojet engine designs? This way,
the engine could still operate at higher altitudes. Also, using an
oxidizer that could absorb sufficient heat from the incoming airstream
(cryogens, maybe...?) would reduce the air temperature, thus allowing
the engine to operate at higher Mach numbers. Where air becomes too
thin, the air inlets could be closed, and the engine would operate in
a purely rocket mode.

Not being an engineer, I have *no* idea what the kind of pitfalls
would be to such a system... but might it be worth exploring?