You have a good point. Just because fish use a tail doesn't mean engineered systems should too. But there are benefits to fin actuation. For example, most all propeller driven subs are rigid, which limits their maneuverability. The flexible body of fin actuation allows the robot to be much more maneuverable. Also, cavitation is a non-issue with fin-actuation. As for efficiency, I suspect you're right that electric motors will be more efficient when driving a prop, especially considering that props have over 60 years of optimization and testing in them.
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You have a good point. Just because fish use a tail doesn't mean engineered systems should too. But there are benefits to fin actuation. For example, most all propeller driven subs are rigid, which limits their maneuverability. The flexible body of fin actuation allows the robot to be much more maneuverable. Also, cavitation is a non-issue with fin-actuation. As for efficiency, I suspect you're right that electric motors will be more efficient when driving a prop, especially considering that props have over 60 years of optimization and testing in them.
Ah yes - that'd be awesome. Except the environmentalists who posted above would never let a thing like that into the pristine ocean.
I can confirm that there is nothing toxic in the robots. Side panels are aluminum and the clear parts are acrylic. Even the PCB is RoHS.