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I guess you'd need a large keel or rudder at the front of the canoe to stop
the aforementioned
side to side movement, wich would be more pronounced being on top of
the water.
Alan
----- Original Message -----
Sent: Friday, December 03, 2010 4:47
PM
Subject: Re: [PSUBS-MAILIST] Fishtail
propulsion
Very true, Alan.
It gets more complicated as you scale it up. As you
wag the tail faster, the forces on the mechanism and structure get pretty
big.
In addition to the propulsion from the sculling
action, a significant portion of a fish's propulsion results from the
vortices generated from the tail motion which is why they can accelerate so
rapidly. It's similar to a whiplash action.
I may or may not be able to get the canoe to move more
easily or conveniently than with a paddle. Or I might just make the
yuloh master laugh.
Jim
In a message dated 12/2/2010 9:17:26 P.M. Central Standard Time,
alanjames@xtra.co.nz writes:
They're pretty good Jim,
I saw some others when I followed the link. One was hard to tell from
the real thing.
Looking at their side to side head movement convinces me that it would
be a bad
form of propulsion for a sub as you'd get sick quickly.
Alan
----- Original Message -----
Sent: Friday, December 03, 2010 3:41
PM
Subject: [PSUBS-MAILIST] Fishtail
propulsion
Frank,
Here are a few videos I found of mechanical fish such as
we were discussing.
At some point just for fun, I might build a rig to try
out on my canoe or a Jon boat. From a top view:
B= body of the canoe
P= the powered section moved left and right
F= fin
x= hinges
BBBBBBBBBBBBBBBBBBBBBBxPPPPPPxFFFFFFFF
When power is applied to P to swing it left and right, F
will swing in the opposite direction (by the force of the
water) to provide propulsion from the sculling motion. P will
move through fewer degrees of arc than F. The range of motion for P
is determined by the configuration of the push/pull rods which power
it. The range of motion for F is determined by stops on the
hinges.
I have several other projects with higher priority, but
maybe one of these days...
Jim
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