Abstract: An articulated blade whose forward vane section is directly pitched by relative fluid flow upon it, and whose rear deflector section deflects the flow upon it. A control arm, through parallelogram linkage, maintains the deflector in parallel orientation with it, thus cambering the blade when it pitches. Fluid is deflected always in a direction controlled by orientation of the control arm. High lift-drag ratios are possible at high angles of attack. The blade can be used to extract power from the fluid, or for propulsion through a fluid.