| Topic: |
Science > Physics |
| User: |
"Externet" |
| Date: |
31 Aug 2006 11:32:54 PM |
| Object: |
Diver fins and propulsion efficiency... |
Hi.
Periodically, there is claims of a "better fin"... Setting aside ALL
marketing strategies from vendors that say such and such model and
design is the best; and focusing to pure physics;
How to determine the most efficient diving fins shape, width,
stiffness, lenght...? Efficient meaning getting the most propulsion
from a given leg stroke force ?
Is it possible that it is only related in analogy to the "impedance
matching" principle in electronics -for who are familiar with it-
(matching leg-strenght to fin resistance-to-move) ? -Whatever be its
equivalent name in mechanics-.
With no doubt, if the fin has an absurd shape, or the user kicks wrong
it won't propel; but what about the determination in real life of what
would make a fin most efficient ?
Miguel
.
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| User: "Sorcerer" |
|
| Title: Re: Diver fins and propulsion efficiency... |
01 Sep 2006 01:23:24 AM |
|
|
"Externet" <externet@inorbit.com> wrote in message
news:1157085173.973224.310410@m79g2000cwm.googlegroups.com...
| Hi.
| Periodically, there is claims of a "better fin"... Setting aside ALL
| marketing strategies from vendors that say such and such model and
| design is the best; and focusing to pure physics;
|
| How to determine the most efficient diving fins shape, width,
| stiffness, lenght...? Efficient meaning getting the most propulsion
| from a given leg stroke force ?
|
| Is it possible that it is only related in analogy to the "impedance
| matching" principle in electronics -for who are familiar with it-
| (matching leg-strenght to fin resistance-to-move) ? -Whatever be its
| equivalent name in mechanics-.
|
| With no doubt, if the fin has an absurd shape, or the user kicks wrong
| it won't propel; but what about the determination in real life of what
| would make a fin most efficient ?
|
| Miguel
Aircraft shapes are determined in wind tunnels, and the swing
wing should give you a clue. The fin that collapses when
pulled forward and spreads when pushed back has an advantage,
think of a parachute or umbrella being closed as you push,
open as you pull.
Impedance matching isn't going to help, all that does
is determine a frequency, not overcome drag.
You might consider fast acting balloons on your feet that
collapse and expand with water pumped from one to the other
and back again, and of course hand fins will help as well.
Androcles
.
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