Abstract: A transition pipe for location between an afterburner pipe and a jet nozzle in a jet pipe assembly for a turbojet engine comprises a funnel shaped inner casing tapering downstream from a circular section at its upstream end to a quadrangular section at its downstream end, a horn shaped outer casing surrounding the inner casing and flared downstream from a circular upstream end section to a downstream end section formed of four joined segments of generally parabolic shape, and a plurality of peripherally spaced, longitudinally extending stiffeners interconnecting the inner and outer casings in the space therebetween.