Abstract: In one embodiment, a propulsion device for use with a fluid may include a shaft coupled to a drive system that rotates the shaft, one or more cranks rigidly coupled to the shaft, and one or more connecting structures that are movably coupled to one of the one or more cranks. A foil may be rigidly coupled to the one or more connecting structures. One or more slide structures or one or more linkages may be coupled to the foil and arranged to restrain movement of the foil when the foil is actuated by the one or more cranks via the one or more connecting structures, such that rotational motion of the shaft is translated to a combination of motion of the foil between an inner extent and an outer extent and motion of the foil within an angular range between first and second limits.

Abstract: In one embodiment, a propulsion device for use with a fluid may include a shaft coupled to a drive system that rotates the shaft, one or more cranks rigidly coupled to the shaft, and one or more connecting structures that are movably coupled to one of the one or more cranks. A foil may be rigidly coupled to the one or more connecting structures. One or more slide structures or one or more linkages may be coupled to the foil and arranged to restrain movement of the foil when the foil is actuated by the one or more cranks via the one or more connecting structures, such that rotational motion of the shaft is translated to a combination of motion of the foil between an inner extent and an outer extent and motion of the foil within an angular range between first and second limits.

Abstract: In one embodiment, a propulsion device for use in a fluid may include a crank-slider mechanism having one or more cranks, one or more connecting rods, a mast, and one or more slide structures. These structures may be 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. A flexible foil may be rigidly coupled to the mast of the crank-slider mechanism. The flexible foil may include a flexible nose portion and a flexible tail portion. The flexible tail portion may have a differing amount of flexibility than the flexible nose portion.

Abstract: In one embodiment, a propulsion device for use in a fluid may include a crank-slider mechanism having one or more cranks, one or more connecting rods, a mast, and one or more slide structures. These structures may be 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. A flexible foil may be rigidly coupled to the mast of the crank-slider mechanism. The flexible foil may include a flexible nose portion and a flexible tail portion. The flexible tail portion may have a differing amount of flexibility than the flexible nose portion.