A rocket engine having guide vanes in the engine nozzle the guide vanes (2) being mounted for turning at or near the rearmost ends of fixed vanes (1) being parallel to the axis of the nozzle and protruding into the combustion chamber of the engine. The foremost ends (4) of the guide vanes (2) may be shielded by the rearmost ends of the fixed vanes (1), and the guide vanes (2) may be individually turnable.