A ducted air power plant, comprising a motor driven fan (7) situated in a duct (4), the fan (7) having an air intake side and in operation providing a high pressure air stream in the duct, and the fan being located adjacent air splitter mechanism (18), the air splitter mechanism (18) being arranged to divert the air stream into two or more subsidiary streams for delivery to respective jet nozzles (9) of the plant. The plant may be used in a vehicle such as an aircraft in order to provide a vertical take-off and hover capability as well a level flight power source.