An automotive fan having flexible curved blades of resilient material which decamber as rotational speed increases in which an integral portion of each blade, having a mass of the order of 2 percent to 40 percent, preferably 8 percent to 10 percent, of the remainder of the blade, extends continuously along substantially the entire trailing edge of the blade and is folded upon itself at the trailing edge on the upstream side of the blade, thereby rigidifying and weighting the trailing edge to reduce vibration and noise and to assist the decambering of said blade at a predetermined rate.