Abstract: An apparatus for propelling fluid, the apparatus including a rotatable propeller disposed within a container. The propeller has at least one entry collector in the form of a hollow cylinder open at one end and closed at the other. A plurality of conduits are aligned in at least one row, the conduits communicating with the entry collector by way of a similarly aligned row of openings. The conduits may be defined entirely within members which present only smooth surfaces to the surrounding fluid. The cumulative inner volumes of the conduits of one row is less than 33% of the volume of an annular body of revolution defined by that body of conduits when in rotation. Also, the inner volume of the entry collector is approximately equal to the cumulative inner volumes of the conduits of that row. The conduits may be positioned at angles other than 90.degree. with respect to a motor shaft which drives the propeller.