[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PSUBS-MAILIST] Fishtail propulsion



For me, the trouble with that hobie design is that while it looks cool, in the waters around here especially you'd have those flipper things snapped off on a rock in about 5 seconds!  Then you'd be litterally up the creek without a paddle!  doh!

On 6 December 2010 15:22, <JimToddPsub@aol.com> wrote:
Good morning, Ian,
 
The Hobie uses reciprocating pedals.  The one I saw in Popular Science uses rotary bicycle pedals and a prop.  It would be interesting to see which produces more thrust.  I think reciprocating pedals are preferable to rotary especially from a seated position no matter which method of final drive is employed .
 
Jim
 
In a message dated 12/6/2010 1:40:44 A.M. Central Standard Time, irox@ix.netcom.com writes:

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



************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003.  Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.

If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
    removeme-personal_submersibles@psubs.org

Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of
our server receiving your request.

PSUBS.ORG
PO Box 53
Weare, NH  03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************