Abstract: A propulsion system for vertical take off and landing aircraft includes a forward compressor fan (40) and an aft compressor fan (42) downstream of the forward fan and in series flow communication with the forward fan. The forward and aft fans are positioned in a central duct (26). A gas turbine engine (44) is in series flow with the forward and aft fans for driving the fans. The forward fan, aft fan and turbine engine are interconnected by a common shaft (50). A forward diverter structure (100) is positioned downstream of the forward fan and is movable between a first position for diverting exhaust from the forward fan downwardly relative to the longitudinal axis of the aircraft while simultaneously permitting the introduction of air behind the forward diverter structure but ahead of the aft fan and a second position wherein the exhaust from the forward fan is channeled through the aft fan and turbine.