>A favorite of mine is Thrust Augmented Nozzle or TAN, where, at low altitudes, extra propellant is injected into the nozzle (not the chamber) and that gets cl

>A favorite of mine is Thrust Augmented Nozzle or TAN, where, at low altitudes, extra propellant is injected into the nozzle (not the chamber) and that gets close to my favorite - air-augmenting regular rocket engine. Very simple and bumps up your thrust and ISP up to 2-3x http://www.astronautix.com/g/gnom.html http://www.astronautix.com/g/gnom.html