How does kicking work?

In sci.physics RichD said:

How does the flutter kick, as in the standard
crawl stroke, produce forward propulsion? An
oscillatory up and down motion, somehow creates
a net force. It's a mystery to me. And how
do flippers amplify that effect?

The same way a fan blade moves air; the surface is at an angle
with the fluid.

Flippers increase the area.

Quoted message said:

PS And why am I the slowest swimmer in the pool?

Too much time on the computer and not enough time in the pool.

Quoted message said:

PPS Are the feet supposed to break the surface on this kick?

Only if you are trying to fly.

Quoted message said:

--
Rich

--
Jim Pennino

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RichD said:

How does the flutter kick, as in the standard
crawl stroke, produce forward propulsion? An
oscillatory up and down motion, somehow creates
a net force. It's a mystery to me. And how
do flippers amplify that effect?

Unlike bacteria, we live in a high Reynolds number world.
Here is a link to a fascinating article describing a
world where the flutter kick would be useless.
http://brodylab.eng.uci.edu/~jpbrody/reynolds/lowpurcell.html

Quoted message said:

PS And why am I the slowest swimmer in the pool?

PPS Are the feet supposed to break the surface on this kick?

Jerry

RichD said:

How does the flutter kick, as in the standard
crawl stroke, produce forward propulsion? An
oscillatory up and down motion, somehow creates
a net force. It's a mystery to me. And how
do flippers amplify that effect?

Unlike bacteria, we live in a high Reynolds number world.
Here is a link to a fascinating article describing a
world where the flutter kick would be useless.
http://brodylab.eng.uci.edu/~j pbrody/reynolds/lowpurcell.htm l

Quoted message said:

PS And why am I the slowest swimmer in the pool?

Quoted message said:

PPS Are the feet supposed to break the surface on this kick?

Don

One reason I'm so fast is because I have stator blading on my legs to
accelerate all the water in the aft direction.

Even eels aren't that advanced.

Bret Cahill

RichD said:

How does the flutter kick, as in
the standard crawl stroke, produce
forward propulsion?

According to Maglischo in Swimming
Fastest, they have theories, but no
definitive proof about why kicking
moves one forward in the water.

Quoted message said:

PPS Are the feet supposed to break
the surface on this kick?

Some do in sprint kicking.

Quoted message said:

Quoted message said:

How does the flutter kick, as in the standard
crawl stroke, produce forward propulsion? An
oscillatory up and down motion, somehow creates
a net force. It's a mystery to me. And how
do flippers amplify that effect?

The same way a fan blade moves air; the surface
is at an angle with the fluid.

This may be correct, in principle, but you
have work to do to show that a flutter kick
operates like a propeller.

Quoted message said:

Flippers increase the area.

Quoted message said:

Quoted message said:

PS And why am I the slowest swimmer in the pool?

Too much time on the computer and not enough time in the pool.

ouch! The truth hurts...

Quoted message said:

Quoted message said:

PPS Are the feet supposed to break the surface
on this kick?

Only if you are trying to fly.

Huh?

--
Rich

In sci.physics RichD said:

Quoted message said:

Quoted message said:

How does the flutter kick, as in the standard
crawl stroke, produce forward propulsion? An
oscillatory up and down motion, somehow creates
a net force. It's a mystery to me. And how
do flippers amplify that effect?

The same way a fan blade moves air; the surface
is at an angle with the fluid.

Quoted message said:

This may be correct, in principle, but you
have work to do to show that a flutter kick
operates like a propeller.

Or a wing or anything else that produces a force at roughly a right
angle to the fluid flow.

Easy to show; tie/tape/glue a bunch of yarn to your legs and feet and
videotape the flow.

<snip>

--
Jim Pennino

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RichD said:

Quoted message said:

Quoted message said:

How does the flutter kick, as in the standard
crawl stroke, produce forward propulsion? An
oscillatory up and down motion, somehow creates
a net force. It's a mystery to me. And how
do flippers amplify that effect?

The same way a fan blade moves air; the surface
is at an angle with the fluid.

This may be correct, in principle, but you
have work to do to show that a flutter kick
operates like a propeller.

Think about how you fan yourself on hot days with a
piece of paper or cardboard, or in a pinch by flapping
your hand. In all cases you are oscillating something
in a plane perpendicular to the desired air flow,
yet you are generating flow against your face.

Quoted message said:

Quoted message said:

Flippers increase the area.

Quoted message said:

Quoted message said:

PS And why am I the slowest swimmer in the pool?

Not if I'm in the pool, too.

Quoted message said:

Quoted message said:

Too much time on the computer and not enough time in the pool.

ouch! The truth hurts...

Have you ever tried to propel yourself by feet alone, using
one of those foam boards they give beginning swimmers?
It's an incredibly slow form of propulsion. Maybe
(certainly) competitive swimmers get a lot more thrust out
of their flutter kick than I do, but I would guess that
the hands and arms generate most of the thrust.

An exception might be the butterfly, where the entire
lower body is flapped.

- Randy

"Randy Poe" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Have you ever tried to propel yourself by feet alone, using
one of those foam boards they give beginning swimmers?
It's an incredibly slow form of propulsion. Maybe
(certainly) competitive swimmers get a lot more thrust out
of their flutter kick than I do, but I would guess that
the hands and arms generate most of the thrust.

An exception might be the butterfly, where the entire
lower body is flapped.

It's difficult to quantify, and of course there are individual variations,
but typically quoted figures are...

for Front Crawl, Back Crawl, and Butterfly in the range from zero to 15-20%;

for Breaststroke, anywhere from 25% to 75%.

In the first (three) case(s), the higher numbers are for good kickers while
sprinting (anything longer than a 200 is not a sprint; swimmers doing such a
race may kick a lot but exercise physiologists would suggest it is probably
not the best strategy).

In the case of Breaststroke, the wide range follows from the great
individual variation in stroke; and being at one or the other end of this
range is no bar to success - or even supremacy.

If you were pidgeon toed you might be able to recoup some of the
vertical movement of water wasted in kicking.

Bret Cahill