Propeller blade or airfoil with hollow composite root

A manufacturing method for a propeller blade or airfoil for a turboprop engine, of composite material, comprising a fibrous reinforcement densified by a matrix, the method comprising:

• producing a one-piece fibrous blank by three-dimensional weaving, the fibrous blank having a flat shape extending in a longitudinal direction and a transverse direction corresponding respectively to a span direction and to a chord direction of the propeller blade or airfoil to be manufactured, the fibrous blank comprising a root portion and an aerodynamic profile portion extending in the longitudinal direction from the root portion and in the transverse direction between a leading edge portion and a trailing edge portion,
• forming the fibrous blank for obtaining a one-piece fibrous preform having said aerodynamic profile portion forming an aerodynamic profile preform portion and said root portion forming a root preform portion, and
• densifying the fibrous preform with a matrix for obtaining a propeller blade or airfoil, of composite material, having a fibrous reinforcement consisting of the fibrous preform and densified by the matrix, and forming a single part with integrated root,
• wherein the root portion of the fibrous blank comprises an unlinked area delimiting an internal root recess opening at a free end of said root portion and extending in the longitudinal direction, said unlinked area extending in the transverse direction between a first lateral edge and a second lateral edge and recessed from said first and second lateral edges, and wherein the forming of the fibrous blank comprises a positioning of at least one insertion element in the internal root recess so as to form a bulb-shaped root preform portion, and
• wherein the root preform portion extends, in the span direction of the propeller blade or airfoil, outside the aerodynamic profile preform portion from a bottom end of said aerodynamic profile preform portion and recessed, in the chord direction of the propeller blade or airfoil, from the leading edge portion and the trailing edge portion of said aerodynamic profile preform portion.