A linerless composite tank for a waste or water system on board an aerospace vehicle includes a monolithic tank body having a first composite material co-cured with a second composite material. The first composite material includes a first resin and the second composite material includes a second resin that is different from the first resin. The first composite material forms an innermost surface of the monolithic tank body defining a tank chamber of the monolithic tank body. A method of manufacturing the linerless composite tank includes providing a mold having a desired interior shape of the monolithic tank, applying the first composite material to the mold, applying the second composite material to the mold, and co-curing the first composite material with the second composite material to form the monolithic composite tank.

A method for manufacturing a stiffened cylindrical part, includes positioning a precursor assembly of the part to be manufactured in a tool, the assembly being made of thermoplastic preimpregnated fibrous material and including (i) a sectorized cylinder, and (ii) stiffening elements present on an internal surface of the cylinder, the tool including an internal part lined with a vacuum bag, facing the internal surface of the cylinder, on which the assembly is positioned, and an external molding part of cylindrical shape, facing an external surface of the cylinder, and the conformation of the assembly on the external molding part and the joining by co-consolidation of the stiffening elements on the internal surface of the cylinder with vacuum draw in the molding tool, in order to obtain the composite material part to which the stiffening elements are joined.