Abstract: A reaction engine, such as a ramjet engine, has a nozzle assembly which maintains acceptable combustion chamber pressures during both high thrust and low thrust modes of flight. To this end, the engine has a primary nozzle in which a swing disc is located, and the disc turns from an open position in which it lies parallel to the axis of the primary nozzle to a closed position in which it lies across and blocks the primary nozzle. The disc contains secondary nozzles which are considerably smaller than the primary nozzle and are only effective when the disc is in its open position. The secondary nozzles may initially be filled with a flow smoothing material to prevent turbulence when the swing disc is in its initial open position, but this material is dislodged when the disc moves to its closed position.

Abstract: A passive chamber wall fragmenter adapted to be mounted on or in connection with a portion of a chamber wall which is mounted to be dislodged by a pressure differential across the wall portion, wherein the fragmenter is adapted to become active upon displacement of the wall portion to cause the displaced wall portion to fragment or break up into small pieces so as to minimize damage that might result from larger pieces striking sensitive structure making up the chamber.