Abstract: The present invention provides an axial flow fan and fan blade. A true tapered, twisted airfoil section is constructed by cutting a flat piece of light alloy to a unique shape to obtain a flat pattern representative of a selected airfoil design, forming the airfoil section by making three simple bends in the pattern and joining the trailing edge with rivets. A transition piece is provided to connect the airfoil section to the fan hub. The transition piece has first and second airfoil bearing surfaces, substantially all of which are in contact with the interior surface of the airfoil section and which possess a twist complementary to the twist of the airfoil section. The transition is substantially flat and is preferably of a two piece design comprising juxtaposed first and second pieces joined along a peripheral flange. The transition piece allows for the use of a generally U-shaped rivet pattern for the mechanical connection between the airfoil section and the transition.

Abstract: A molded, composite, airfoil-defining, synthetic resin blade for large diameter cooling tower fans is disclosed wherein a moderately dense synthetic resin foam core is first formed that is generally of the same size and shape as the final desired blade. A shank embedded in the foam core extends outwardly from the end of the blade that is adapted to be fastened to the fan hub. A skin of fiberglass reinforced synthetic resin material is placed over the foam core with the thickness of the skin being greatest at the hub end of the blade and especially around the shank. The foam core with the skin thereon is molded into the final desired configuration thereof under pressure and temperature conditions such that the core is compressed and the thickness reduced to an extent correlated with the thickness of the synthetic resin skin on opposite faces thereof.