Abstract: A variable speed centrifugal pump for aircraft fuel systems and the like having the capability of matching fuel flow and pressure to engine requirements throughout a variable flight profile without in-line flow controls and metering devices comprising a unique combination of centrifugal impeller stage and positive displacement pump device which controllingly, drivingly, fluidly couples the impeller to the aircraft engine drive. The positive displacement pump device includes rotating hydraulic displacing input and output members, the latter being driven by the former at a relative speed normally responsive to discharge flow rate of the positive displacement pump device which is controlled to regulate impeller speed for matching pump flow and pressure to engine requirements.