Contoured sheet metal airfoil fans

A fan assembly, comprising:

• a. a multiple number of sheet metal blades useful for impelling air and having a predetermined curvilinear air foil contour,
• b. a multiple number of blade roots each integral with one each of said blades, and having substantially all portions thereof constructed of a single ply sheet metal, said root having a curvilinear web extending from said blade along an axis of said blade disposed between the leading and trailing edges of said blade, said root having symmetrically arranged wing portions extending from leading and trailing edges of said web, said wings for each of said blade roots comprising a tab extending substantially along the entire leading or trailing edge of said web,
• c. a hub formed of at least one pair of single ply discs each joined at a central zone and separated to form a hollow ring at a radially outer zone, said hollow ring having circumferentially spaced receptacles for receiving each of said blade root assemblies and to enclose at least part of said tabs, said hub receptacles having flanges which extend toward the root assembly with the edges of said flanges terminating to form a mating relationship with the contour of said web, said hub further having means for securing said root assemblies within said receptacles against relative rotary movement therein, said hub means comprising slots complimentary in shape of said tabs and receiving said tabs for extension therethrough.