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> >A swimming tail is not only less efficient for straight line travel it is
> >horrendously complex compared to a propeller.
>
>Why is it less efficient?
Many years ago when energetics of motion was a research subject in vogue
several groups published graphs showing relative efficiencies of swimming,
bicycling, flying etc etc. A swimming fish of a given mass and speed used a
lot more oxygen than of a boat with a propellor. Alas I do not have the
references handy but I'll snoop around.
> >If you don't want a conventional drive, what about magnetohydrodynamic
>(visa vis Red October)?
>
>Well, for one thing, MHD drive requires supercondutor style magnets, liquid
>nitrogen, and other ultra-high tech and high $$$ equipment. I was thinking
>along the lines of simplicity. If two slabs of peizo-plastic in a
meta-tail >and $10 computer controller to make the motion does it, then it
doesn't seem >all that complex to me.
Well, the motion of a fish (or dolphin) tail is more coplexx than simply
flapping back and forth. You may need more than one or 2 slabs of
peizo-plastic in your meta-tail and I suspect a computer with enough power
to monitor local water pressure, local thrust (across the meta-tail) etc etc
is going to cost more than $10. All this needs to be powered also.
Temperature is a problem fish have with their energetics. I believe Tuna
solve this by being warm blooded but then, they are voracous feeders as
well. Comment from the icthyologists?
As to superconducting magnets, once they are superconducting don't they stay
that way? I thought the whole appeal of MHD was that it was more efficient
than a propellor (no turbulence). If you want liquid nitrogen (or even
liquid helium) we have some here.
What about a MHD scooter for dragging divers around instead of those
propellor powered things.
>I'm not "telling", I'm "asking"... ???
I'm not "telling", I'm discussing.
Have a nice day.
/rat
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
shelps@ac*.ma*.ad*.ed*.au*|Stephen Helps PhD Ack! ___/|
FAX (08)232-3283 |Anaesthesia & Intensive Care \O.o|
Voice (08)224-5495 |University of Adelaide =(___)=
|ADELAIDE, 5005, South Australia U
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"It's not denial. I'm just very selective about what I accept as reality."
--- Calvin ("Calvin and Hobbes")
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