Ducted fan

摘要

A ducted fan including a funnel-shaped duct positioned upstream of the impeller and connected to a base, an outer cowling concentrically positioned downstream and attached to said duct through a series of ribs, an inner cowling positioned inside the outer cowling and surrounding the impeller and a circular grill attached to the discharge end of the inner cowling. The grill including a center hub and a series of arcuate-shaped ribs extending outwardly from the hub and having a constant curvature of less diameter than the outside radius of the grill whereby the maximum lateral spacing between the ribs is at a radius inboard from the outside radius of the grill.