Abstract: One piece hollow airfoils are manufactured from molded carbon filament materials, with internal support structures integrally formed in a single closed mold operation. The outer skins and the internal reinforcement structure all are cured together as an integral unit. To accomplish this, a mold having a cavity defining the outer shape of the airfoil is opened. Precut, pre-preg fiber material and core material then is placed in the mold halves. At least two adjacent elongated resilient mandrels are placed in contact with the precut sheets of pre-preg fiber to press the sheets and core into contact with the mold upon subsequent closure thereof. An elongated web of pre-preg fiber material is placed between the adjacent mandrels, and in contact with them, to cause said edges of the web to contact the sheets of pre-preg fiber material on opposite sides of the mold cavity. The mold is closed; and heat is applied to cure the pre-preg fiber material and to bond the web with the precut sheets.