Fish-like propulsion

[Boston]

Im not going to attempt any arguments for intelligent design ( dam poor excuse for science ) but I would point out that the basic bacterial flagellum fits that description



also illustrated



Some bacteria boast a marvelous swimming device, the flagellum, which has no counterpart in more complex cells. In 1973 it was discovered that some bacteria swim by rotating their flagella. So the bacterial flagellum acts as a rotary propellor -- in contrast to the cilium, which acts more like an oar.

The structure of a flagellum is quite different from that of a cilium. The flagellum is a long, hairlike filament embedded in the cell membrane. The external filament consists of a single type of protein, called "flagellin." The flagellin filament is the paddle surface that contacts the the liquid during swimming. At the end of the flagellin filament near the surface of the cell, there is a bulge in the thickness of the flagellum. It is here that the filament attaches to the rotor drive. The attachment material is comprised of something called "hook protein." The filament of a bacterial flagellum, unlike a cilium, contains no motor protein; if it is broken off, the filament just floats stiffly in the water. Therefore the motor that rotates the filament-propellor must be located somewhere else. Experiments have demonstrated that it is located at the base of the flagellum, where electron microscopy shows several ring structures occur.



by way of disclaimer some of this info has been used by the nut jobs on the far right to argue intelligent design and although the simple science is pertinent to this discussion I consider its relevance to any arguments concerning space men or gods to be somewhat less than tenable

my two cents
B

[ancient kayaker]

The flagellum would seem a good example to suport an argument against intelligent design! Thanks for the explanation, I hadn't realized it actually rotates.

Of course, the flagellum concept doesn't actually need a fully rotating bearing, the same motion can be generated by a whip with a 90 deg elbow, which is how I assumed they worked.

Since we're looking for alternative propulsion methods, here's one I don't remember seeing before. It works like the arm motion in the breast stroke, although it is just a variant on the oar principle. I'm not sure how the mechanical aspects could be handled but it is not an insuperable problem.

[Boston]

not only does it rotate but if you look at how its constructed its only a mater of time before they find a way to "discover" its a bio-electric motor
all they need do is map the chemical interaction and it should come clear
problem is most of that kind of thing is cutting edge and only done on nerve cells with this oddball type of microscope that uses wave cancellation
cant remember what its called

[ancient kayaker]

Some exotic variant of the Electron Microscope I assume?

[Boston]

actually no it is able to observe live samples as aposed to the prepared and thoroughly dead kind that a scanning microscope like the electron does


basically it takes a laser beam splits it
sends one through the sample
reverses the frequency of the other
recombines the beams
canceling out the similar properties
and what is left is then analyzed and collated into a data stream
the result is a live 3d moving image of objects in the 5 to sa 15 nanometer range
I probably shouldn't be discussing it as its still in the experimental phases but I dont think the microscope police are listening
at the moment I think its only being used to study the chemical interaction of neural dendrils in mice

[sigurd]

AK - that is strange. I thought at first it was flapping, like the mirage hobie kajak drive, but from the description it sounds like the lower illustration is from the top, and both arms are counter rotating.

[ancient kayaker]

Sigurd: that's correct.

Boston: sounds like it's related to holography.

[Boston]

no its kinda its own animal
I had lunch up in Boulder the other day with the inventor
or one of em
there fighting over it
so its kinda all on hold and has been for a few years

[Guillermo]

Gymnobot:

http://www.bath.ac.uk/news/2009/09/21/robot-fish/

http://images.google.com/images?q=gy...ed=0CCQQsAQwAw

Cheers.

[fastfreddy]

Originally Posted by Senyorita

Guys, any ideas on alternative (say fish-like) propulsion for a small personal submarine?

Check out the original "Batman Movie". The Penguin had a sub with fins for propulsion.

[kach22i]

The tiny propeller on this RC boat out powers a catfish as large as the boat.

What does this imply about efficiency of the two opposing propulsion systems?

http://www.youtube.com/watch?v=D3kqL_6xEtE