Abstract: A propulsion nozzle of a gas turbine engine comprising two mutually confronting spaced fixed side walls 14, 16 and two upper and lower mutually confronting spaced movable walls 20, 22 which locate and move in trackways 18 in the side walls. The movable walls 20, 22 each comprise a plurality of pivotally interconnected members which extend transverse to the fixed walls to define a convergent part and throat of the nozzle.A flap 28 is pivotally connected at its upstream end to a downstream end of one of the movable walls 20(b) and is operable, in at least one mode of operation, to cooperate with the fixed walls to define a divergent expansion ramp downstream of the throat of nozzle. In a first mode of operation, the movable walls 20, 22 can be moved along the trackway 18 to cause the members to define a con-di nozzle facing rearwards to produce forward thrust.