Unfoldable divergent nozzle for a rocket engine

An unfoldable divergent nozzle for a rocket engine, having an inner wall and an outer wall and comprising a neck, a fixed upstream portion and a set of elementary individual panels of refractory material articulated to one another and with respect to said fixed upstream portion of said divergent nozzle in the vicinity of said neck of said nozzle, said articulated panels being distributed so as to define at least two successive adjacent rings or frustums and positionable in a first folded position then in a second unfolded position, each said panels having an inner surface for forming a portion of said inner wall of said divergent nozzle, and an outer surface for forming a portion of said outer wall of said divergent nozzle, wherein articulations are provided between two adjacent panels arranged to be folded on one another with their inner surfaces facing one another, each said articulation comprising at least one hinge with two axles inserted in the walls of said two panels articulated to one another, a link being set back with respect to the thickness of said panels and holding said two axles at a constant distance from one another, and wherein two cylindrical surfaces centered respectively on each of said axles and capable of rolling without sliding on one another are arranged on two adjacent panels in the vicinity of said hinge, said two cylindrical surfaces of one articulation centered respectively on each of the axles and rollable without sliding on one another being made of a refractory material and being provided with teeth which are built up on the panels bearing the cylindrical surfaces and are formed of a fusible material.