Vessel propelled by oscillating fin with control mechanisms

Abstract

A marine propulsion system emulates the fishes swimming motion yet is highly maneuverable as it permits changes from forward to reverse motion while underway. In other aspects, the propulsion system may be designed and optimized for efficient human powered propulsion.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claim priority to U.S. provisional patent application entitled “VESSEL PROPELLED BY OSCILLATING FIN WITH CONTROL MECHANISMS”, filed May 14, 2003 and having Ser. No. 60 / 470,954, which is incorporated herein by reference.BACKGROUND OF INVENTION [0002] The present invention relates to marine propulsion systems and methods, more specifically to a marine propulsion system that is highly efficient, in part, through emulation of a fishes swimming motion. [0003] U.S. Pat. No. 5,000,706 to Wang having issued on Mar. 19, 1991 teaches a rocker arm type propulsion mechanism for a personal water craft type boat which emulates some aspects of a fishes swimming motion. However, Wang's mechanical assembly is complex and inconvenient in the manner in which it controls thrust magnitude and direction. Further, the boat lacks efficient means for steering, dynamic stabilization and control and other practical requirements of watercraft hand...

AI Technical Summary

Benefits of technology

[0009] In contrast to marine animals, another aspect of the present invention is a method and apparatus to generate the heaving and pivoting motion. This apparatus is not submerged and may be located above the surface of the water, with only the airfoil section of the propulsion fin immersed in the fluid. The propulsion system generates thrust using the principle of lift generated by an airfoil shaped fin of finite span moving through a fluid at some relative velocity and angle of attack. In common with marine animals, and in addition to the hydrodynamic lift generated by the airfoil, the periodic heaving and pitching movement of the airfoil generates a vortex wake structure known as a “reverse Karman street”, whereby the opposing direction of rotation of the alternating vortices is though to create a “jet” of higher velocity water between them along the wake longitudinal centerline, thereby improving the propulsive efficiency. It is also thought that reversal of circulation around the fin upon heave-cycle reversal is enhanced by close proximity to the unbound vorticity from the previous heave half-cycle. Propulsion efficiency can therefore be enhanced by operating the propulsion system in a manner that exploits the existence of these wake vortices.

[0013] In yet another aspect of the invention, the propulsion system optionally employs tunable energy storage devices for efficient torque / displacement matching of the operator / driver and the rest of the propulsion system. The propulsion system can be configured to exploit the energy storage and resonance characteristics of its torsional pendulum configuration. It is possible to tune the torsional natural frequency of the system for beneficial purposes by changing spring stiffness and / or changing the location of a tuning mass along the tail arm boom. Mass may also be added to, or the location of the mass adjusted on a forward extension of the clevis, which will provide improved static and dynamic balance. Mass may also be added or removed from the pylon crank arm.

[0015] Yet a further aspect of the invention is characterized in that a maneuvering and dynamic stabilization system is provided which is capable of providing steering, braking, stabilization of roll / yaw oscillations, and obstacle / debris clearance functions, and which may be controlled by a human operator and / or microprocessor based control system. The maneuvering system exploits the ergonomic benefits and simplicity of a single control handle and single throttle control, facilitating human coordination between and sequencing of propulsion, maneuvering, retraction and throttle actions. The maneuvering system is hydrodynamically and statically balanced, and throttle position automatically maintained in set position, thereby enabling hands-free operation, if desired.

Problems solved by technology

However, Wang's mechanical assembly is complex and inconvenient in the manner in which it controls thrust magnitude and direction.

Further, the boat lacks efficient means for steering, dynamic stabilization and control and other practical requirements of watercraft handling.

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