SSTO propulsion overview

I agree that hypersonic SCRAMJET propulsion research is completely
pointless.

But there is a region between standstill and about mach 6 where air
breathing propulsion is very attractive. Simple calculations show that
you can achieve a factor of 10 savings in fuel consumption if you use
ramjet like engines.

If your design is correct you get a 15 to 1 air fuel mixture ratio
which results in an Isp of about 4000 at standstill. As you start to
move the mass flow increases and the engine leans out, just getting
better and better with speed, up to about 2km/s at which point it is
just easier to close the air intakes and use on-board oxidizer.

There have been numerous real hardware experiments and proofs of
concept that show the performance of ramjets, ejector ramjets, strut
jets etc. An example of an air augmented rocket is the russian GNOM
missile see:

http://www.astronautix.com/lvs/gnom.htm

This missile has less than half the mass of a rocket.

Basically my calculations show that you can save the entire first
stage if you build an air breathing booster. I have actually invented
and built an engine, see at vtol.net that gets an Isp of 4000 at
standstill. An air breathing rocket can be built that uses air first
and then switches to on board oxidizer and gets into orbit with an
overall mass ratio of 6. See also vtol.net/air.htm

I keep repeating myself, nobody ever reads the archives. It is very
easy to search for stuff and read it.

Zoltan