Re: [Paddlewise] Greenland Paddles - Seeing the Flow.

From: Michael Daly <mikedaly_at_magma.ca>
Date: Wed, 08 Sep 2004 14:24:14 -0400
On 8 Sep 2004 at 10:06, Robert MacDonald wrote:

> I knew someone would point this out.  You can't see the flow, if it is
> working right, but you can see the vortex, deep in the water, you can
> see the turbulence created when imperfections on the leading edge trip
> the flow, you can see the air sucked down the blade if it ventilates,
> and you can see the immense amount of turbulence when the blade
> stalls. 

Unfortunately, it forces you to make the further assumption that the 
ventilated blade works the same as an unventilated etc.  Given the 
substantial difference in density between water and air, I'm 
doubtful.

> No doubt these are gross effects, and we would be better off
> studying this stuff at the invisible stage, but this whole problem is
> still at the gross effects stage.

Too true.

>  It is good enough to get the hang
> of how to use the paddle.

Maybe.  However, unless you have a good understanding of 
hydrodynamics, you may not make the correct interpretations.  Don't 
forget that for aerodynamics, most folks expect pointy noses on 
rockets but rocket designers don't often do that.  Expectation leads 
conclusion.

There is even one GP enthusiast who claims to be an expert in 
aero/hydrodynamics who nonetheless had made some of the most specious 
and unsupportable claims about what a GP can do.  Even "religious 
belief" can result in incorrect assumptions among supposed experts.

Mike
***************************************************************************
PaddleWise Paddling Mailing List - Any opinions or suggestions expressed
here are solely those of the writer(s). You must assume the entire
responsibility for reliance upon them. All postings copyright the author.
Submissions:     PaddleWise_at_PaddleWise.net
Subscriptions:   PaddleWise-request_at_PaddleWise.net
Website:         http://www.paddlewise.net/
***************************************************************************
Received on Wed Sep 08 2004 - 11:21:54 PDT

This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:31:17 PDT