Abstract: A nozzle/valve device for a ducted rocket motor is provided. The nozzle/valve device employs a design in which a nozzle throat blockage element can be moved by translational motion within the nozzle throat section of the device. The blockage element is designed so that in the closed position the nozzle throat has a minimum cross-sectional flow area and therefore the nozzle throat is never fully closed. The seals employed in the nozzle/valve device are isolated from contact with reaction products of the gas generator and effective use of minimum amounts of erosion resistant materials is achieved.