Mike wrote: "One thing I learned in studying and working in hydrodynamics - you can't see the flow. At least not with some specific markers in the water (dye etc). I know a lot of paddlers see surface effects and then make assumptions about what's happening, but that's not the same thing as seeing what is happening." 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. 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. It is good enough to get the hang of how to use the paddle. Rob. *************************************************************************** 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/ ***************************************************************************
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/ ***************************************************************************
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