Development of a hybrid propulsion concept has created the requirement for a lightweight nozzle system capable of withstanding gas temperature in excess of 6200 F with condensible soilds in excess of 25 by weight for operation longer than 30 seconds. A series of nozzle material test firings illustrated that tungsten impregnated with copper nozzle provided the best service. This led to the possibility that a transpiration effect or mass transfer cooling was being realized. A test program is now in process making use of pressure-driven liquid metal cooling through tungsten and graphite matrices subjected to a plasma-arc heat source. Tests indicate that liquid metal transpiration coolants, through a tungsten matrix coupled with nozzle inlet sacrificial materials, allow the possibility of longtime operation of a self-contained nozzle system suitable for hybrid or solid propellant rocket propulsion motors. Author
Also available as Rept. no. GIDEP-563.55.00.00-X7-06.