Patent ID: 8784148

Claim:
A propulsion device for use with a fluid, comprising: a crank-slider mechanism including one or more cranks rigidly coupled to a shaft, one or more connecting rods that are each movably coupled to one of the one or more cranks, the movable coupling to permit rotation therebetween, a mast rigidly coupled to each of the one or more connecting rods, one or more slide structures having a channel through which the mast extends, wherein the one or more cranks, one or more connecting rods, and the one or more slide structures are arranged so that rotational motion of the shaft is translated to a combination of substantially linear motion of the mast between an inner extent and an outer extent and rotational motion of the mast within an angular range between a first limit and a second limit; and a flexible foil rigidly coupled to the mast at an attachment point, the flexible foil including a flexible nose portion extending from a leading edge of the flexible foil to the attachment point, and a flexible tail portion extending from the attachment point to a trailing edge of the flexible foil, wherein the flexible tail portion has a differing amount of flexibility than the flexible nose portion.