Abstract: A variable configuration final nozzle assembly for a combined rocket/ramjet engine consists of a fixed annular plug 20 together with upstream and downstream arrays of flaps 10,14 pivoted to the wall of a jet pipe 1 at their upstream and downstream ends 12,16 respectively. In the rocket mode of operation the upstream and downstream flaps are pivoted inwardly and locked in contact with the annular plug to form convergent and divergent portions 2,4 of a nozzle for the rocket exhaust which passes through the plug where a nozzle throat is defined by the internal surface of the plug. In the ramjet mode of operation the flaps lie alongside the jet pipe wall and ramjet exhaust gas flows through and around the plug. A second throat 50 is defined for the flow through the annular nozzle surrounding the plug and flow conditions in both parts of the flow are matched.