Abstract: Multiple, timed three-lobed rotor that are more efficient yet uncomplicated and easy to produce. A rotor lobe with additional reaction surfaces near the tip to increase the angle of rotation that produces power. A “flow through” rotor having end plates that facilitate mounting more than one rotor on a common axis with rotationally varied timing and sequence, such that power delivery is smooth. A flow shielding and directing device that increases the efficiency of reaction surface rotors. Possibilities include replacement or augmentation of: existing electrical energy prime mover dynamos, air compressing, pumping, milling, and other power needs. The dynamo can be built using low-tech, low-cost materials and methods, and is inherently resistant to over speed and damage from periodically high velocity fluid flow.