In one aspect, a device for providing propulsion in water is provided by the present disclosure. The device includes a parallel mechanism including at least five rigid bars and at least five joints, each joint being positioned between two of the rigid bars and configured to allow movement of the at least five rigid bars, a first servo motor coupled to a first rigid bar included in the at least five rigid bars, a second servo motor coupled to a second rigid bar included in the at least five rigid bars, and a controller coupled to the first servo motor and the second servo motor and configured to actuate the first servo motor and the second servo motor according to a predetermined pattern.

A watercraft comprises a motor, an inertial mass, and a fin. The motor oscillates the inertial mass about an axis, producing a torque reaction on and oscillation of the motor. Oscillation of the motor is communicated to the fin, producing thrust.

A watercraft comprises a motor, an inertial mass, and a fin. The motor oscillates the inertial mass about an axis, producing a torque reaction on and oscillation of the motor. Oscillation of the motor is communicated to the fin, producing thrust.

A robotic fish comprises one or more torque reaction engines and a fish body, wherein the torque reaction engine cyclically oscillates and causes a wave to propagate across the fish body, including through a flexible wing, accelerating thrust fluid and propelling the robotic fish.

A robotic fish comprises one or more torque reaction engines and a fish body, wherein the torque reaction engine cyclically oscillates and causes a wave to propagate across the fish body, including through a flexible wing, accelerating thrust fluid and propelling the robotic fish.

A robotic fish comprises one or more torque reaction engines and a fish body, wherein the torque reaction engine cyclically oscillates and causes a wave to propagate across the fish body, including through a flexible wing, accelerating thrust fluid and propelling the robotic fish.

A robotic fish comprises one or more torque reaction engines and a fish body, wherein the torque reaction engine cyclically oscillates and causes a wave to propagate across the fish body, including through a flexible wing, accelerating thrust fluid and propelling the robotic fish.

A robotic eel may comprise a plurality of torque reaction engines, an inertial mass, and a fin. Each of the plurality of torque reaction engines oscillates an inertial mass about an axis, producing a torque reaction on and oscillation of an external shaft. Oscillation of the external shaft bends a beam of the robotic eel. Bending the beam of the robotic eel produces at least one of a traveling or a standing wave in the beam. The traveling wave may be communicated to a second torque reaction of the plurality of torque reaction engines and to the fin, producing thrust.

A robotic eel may comprise a plurality of torque reaction engines, an inertial mass, and a fin. Each of the plurality of torque reaction engines oscillates an inertial mass about an axis, producing a torque reaction on and oscillation of an external shaft. Oscillation of the external shaft bends a beam of the robotic eel. Bending the beam of the robotic eel produces at least one of a traveling or a standing wave in the beam. The traveling wave may be communicated to a second torque reaction of the plurality of torque reaction engines and to the fin, producing thrust.

An exhaust system for a combustion engine vehicle includes an exhaust pipe extending between an exhaust inlet disposed opposite an exhaust outlet. The exhaust inlet and exhaust outlet are in fluidic communication with one another. The exhaust inlet is configured to receive an exhaust gas produced by an internal combustion engine of the combustion engine vehicle. A second pipe has an air inlet extending from and connected to the exhaust pipe. The second pipe is configured to be in fluidic communication with the exhaust outlet. The air inlet is configured to receive an outside flow of air. The exhaust gas from the combustion engine vehicle and the outside flow of air captured by the air inlet when the combustion engine vehicle is moving forward are configured to be combined and to cooperatively exit out the exhaust outlet.