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Re: [PSUBS-MAILIST] Fishtail propulsion
I think this is the peddle powered kayak propulsion device
that was being referred to:
http://www.hobiecat.com/kayaks/features/miragedrive/
Two flippers that move through a 180degree arc.
As for a submarine with a tail, if you want to eliminate
excessive movement of the passenger compartment, then try
two tails operating on the same plane, but in opposite cycles.
The effects of the tail motion on the passenger compartment
should cancel each other out giving a smooth ride. Maybe.
Here is a 1ATM submarine with two tails that can be operated
in opposite cycles:
http://www.nuytco.com/products/exosuit.shtml
Cheers,
Ian
-----Original Message-----
From: JimToddPsub@aol.com
Sent: Dec 5, 2010 7:49 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Fishtail propulsion
Stew, you're in New South Wales, aren't you?
Although I'm very healthy I certainly won't live long enough
to fabricate every Rube Goldberg device that comes into my mind.
Hopefully just conceptualizing some of them will teach me something that might
actually be applicable and useful.
I think any biometric manned submersible would still have only one pressure
hull for occupants. Any more than that would also have to include a large
supply of sick sacks. Even with a single occupied hull you would have to
devise a method to counteract the left and right motion to avoid motion
sickness.
I know there is a commercially available kayak with a prop driven by a
bicycle type mechanism. The shaft goes vertically right through the bottom
of the kayak.
Cheers,
Jim
In a message dated 12/5/2010 8:53:07 P.M. Central Standard Time,
stew@terminalsolutions.biz writes:
Ive
seen kayak’s/canoe’s here with a pedal powered “fin” under the centre of the
kayak… it moves up and down and angles itself as it moves so you get forwards
propulsion! J
it doesn’t have to be a sideways motion (dolphins and whales move their tails
up and down not side to side J
…. And if its on the centre line of the sub… dive planes could be automated to
counter any up and down movement created by the fin’s drag in the water…
Thinking
outside the box…. I know its hard (read impossible) to build flexible pressure
proof joints… but in the future how about a flexible submarine? Like a snake…
the centre portion could remain level, with occupants inside, and the other
front and rear joints could create propulsion and manoeuvring… much like those
autonomous snake robot’s! J
a multi segmented sub… hydraulic rams between each section… you could even
seal each section off from each other while under way… so each section is
actually separate and then use the hydraulics to align the segments, seal them
so you can walk from one end of the sub to the other when its not underway, or
running off secondary propulsion… no flexible joints that way J
Stew
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Alan
James
Sent: Friday, 3 December 2010 3:10 PM
To:
personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST]
Fishtail propulsion
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 -----
From: JimToddPsub@aol.com
To: personal_submersibles@psubs.org
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 -----
From:
JimToddPsub@aol.com
To:
personal_submersibles@psubs.org
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.
http://www.youtube.com/watch?v=eO9oseiCTdk&NR=1
http://www.youtube.com/watch?v=RFgz2pEimu4&NR=1
http://www.youtube.com/watch?v=1QGyxfigkCY&NR=1
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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