RE: [Paddlewise] Testing

On 23 Sep 2004 at 9:10, Colin Calder wrote:

> We also actually do know a lot about paddles from collective
> experience. Wing paddles, and greenland paddles in particular only
> work effectively through specific angles of attack, which change
> dynamically throughout the catch and stroke. If you fail to replicate
> that complex motion (be you a tank test dummy or a novice paddler),
> then they don't do very much very well.

What we know about paddles is largely subjective - well, certainly 
for GPs and non-racing paddles.  I know of many GP users who make 
very different assessments of their paddles after years of use.  
There are very different claims about cadence, efficiency etc. 

In a tank test, we could keep varying the parameters (such as the 
stroke length and cadence, the angle of attack, etc) and objectively 
measure the performance.  If the person conducting the tests is in 
any way creative, they will follow a trend to see where it takes 
them.

Aside: There seems to be a tendency among the general public to 
assume that scientists blindly follow a narrow path and believe 
everything they see.  Having spent a number of years in research 
(both at university and in the business world), I know this is far 
from the truth.  Given any interesting problem, a good researcher 
won't want to quit until they've tried everything they can think of - 
including some really oddball ideas.  I can honestly say that the 
researchers I've known have been among the most creative and 
imaginative people I've ever met - more so than many of the artists 
I've known.  This is backed by psychological studies that show 
scientists and engineers think more abstractly than artists; the 
latter tend to be very concrete thinkers.  This is entirely opposite 
to general perceptions.

> my argument is the only way to test the validity of
> an analysis of the fluid dynamics/mechanics of a static paddle in
> flowing water or a paddle stroked through air and water would be
> through a comparative methodology (combined or not with an analysis of
> the bio-energetics) investigating real paddlers proficient in the use
> of their paddles. Another analogy - Knowing about the fluid dynamics
> of a disembodied swimmers arm would tell you what? yet small changes
> in the complex motion of that arm result in great changes in swimming
> performance.

How far apart should the fingers be to maximize the swimmer's power?  
A test of a disembodied arm can tell you that more accurately than 
any swimmer could.  Once you know that, you can teach the swimmer to 
use it.  

Another example is skiers - they get in wind tunnels to measure the 
resistance of various body positions.  This is something that cannot 
be done without the wind tunnel.  No snow, no bumps, no screaming 
fans - just wind.

If we want to really understand the paddles, there are several steps 
we need to take.  One is to analyze the paddle in various flows so we 
can make some concrete statements about lift vs drag, performance vs 
angle of attack, steady state vs pulsed/dynamic flow changes and so 
on.  Once we know that, then we can then analyze the way in which the 
paddle is used by competent paddlers - what is the flow vs time 
within the stroke.  Then we can use the two groups of information to 
determine whether the paddle is used optimally.

Both the tank and the paddler will come into the situation.  One 
without the other is a waste of time.  I think that from a point of 
view of complete understanding, don't jump the first step.  However, 
the origin of this thread (Peter's proposal to estimate efficiency 
with cheap and dirty tests) is a legitimate step along the way.  It 
won't tell us everything, but it could settle one argument*.

Mike
* and probably start another :-)
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