Abstract: The invention provides a method of making a fiber ply for forming a preform of a composite part in the form of a body of revolution having a non-developable surface, the method being characterized in that it comprises the steps consisting in: defining an annular space (23) with first and second canvases (20, 21) respectively defining an inner periphery and an outer periphery thereof; placing fibers between the canvases (20, 21) by placing the fibers in the annular space in at least one direction and by holding said fibers on the canvases by stitching; implementing circular connection stitching in the vicinity of the inner periphery of the annular space (23); and cutting out the fiber ply as made in this way in the annular space (23) in order to extract it from the canvases.

Abstract: The invention relates to a method of making a casing-and-diverging-portion unit, the method comprising the following steps: forming fiber reinforcement from a first fiber preform made with a first type of fiber and a second fiber preform made with a second type of fiber different from the first type of fiber, said second preform being placed on the first preform; maintaining the fiber reinforcement in tooling so that it has a shape identical to the shape of the casing-and-diverging-portion unit that is to be made; and impregnating said fiber reinforcement with a thermosetting resin and impregnating the resin.