GenCorp Aerojet has successfully tested an engine with a thrust-augmented nozzle, which provides a 29% thrust increase for possible use in the US Air Force-NASA Space Launch Initiative programme. The hydrogen/oxygen-powered Thrust Augmented Nozzle injects and burns additional propellants downstream of the nozzle throat and into the flowpath of the engine early in flight to increase thrust, rather like an afterburner on a jet fighter.
Source: Flight International