Patent ID: 8876038

Claim:
A ducted fan for a VTOL vehicle comprising: a substantially cylindrical duct having an inlet at an upper end and an outlet at a lower end, and an air mover unit located within said substantially cylindrical duct; wherein said substantially cylindrical duct includes inner and outer wall portions and a substantially annular upper lip connecting said inner and outer wall portions, said substantially annular upper lip defining said inlet and having opposed fore and aft portions and opposed side portions; said peripheral lip provided with at least first and second openings, respectively, at each of said opposed side portions of said substantially annular upper lip, said first and second openings permitting flow of air into at least first and second chambers formed within said duct, said first and second chambers connected by at least one passageway to thereby enable substantial equalization of surface pressures at said opposed side portions of said substantially annular upper lip; wherein said at least one passageway is gated to control air flow between said first and second chambers.