Re: [Paddlewise] Racing and paddles with hydrofoil shape

Julio wrote;

>
>Racing is different because races normally take place in ideal and
>controlled conditions. Racing boats are not designed to roll and move
around
>rocks and waves, neither racing paddles. Racing gear is designed to
>maximize the efficiency of the human body motion to move forward in
>ideal conditions. If the conditions were variable, race results could
>not be compared against each other, and one wave would determine who
>is first and second in a race regardless of the quality of the athelete.

I question whether racing is only for ideal conditions. There are a number
of open water races Dan certainly whitewater racing includes plenty of
rocks, manoeuvring etc.  The Caveman put out a video of racing across the
Molokai Channel. Would you call those ideal conditions? I am not yet
convinced that ones opinion on these things constitutes proof of anything.
Basically Julio's opinion could be sound but someone else with as good as
or
better  credentials could have (and do have) opposing opinions. I guess I
must be from Missouri. One should have to prove a thing not just state it
is so unless it is prefaced with a disclaimer that it is purely opinion in
which case one can take or leave it. Not so?
>
>> In other words you are saying that the Greenland paddle works like a
wing
>> except in a horizontal direction instead of vertically?
>
>The lift of the wing has a vertical and a horizontal component.
>The vertical component is upward in wing paddles, and downward in
>Greenland paddles, unless they are use for sculling or bracing.

How do you know this? If the lift is downward how
does it pull the boat forward?  Maybe using Cartesian co-ordinates would
clarify what you are saying.
>

>> Suppose someone said that they had done this test already and discovered
>> it was not valid?
>
>Then I would be happy to know that I do not have to do that test myself.
>Has it really happened? Could you give me a pointer to the tests so
>I can find out what, and how, they were testing. Could explain
>why the test, or the idea of the NACA profiles was not valid.

I was just asking what your response would be not suggesting that such a
test had been done (it may have been) . The reason I ask is that a lot of
the Greenland paddle
stuff has the appearance (to me anyway) of a lot of subjective opinion
masquerading as fact. What I am seeking are quantifiable facts. If there
are none it is not a sin but at least one knows what kind of credibility to
attach to the opinions.

This, of course is not to say that you would respond that way since I
suspect that you would prefer facts as well.

In the meantime Fluid Dynamic Drag by Hoerner and Theory of Wing Sections
by Abbott and Doenhoef might be a good place to start.

Cheers,
John Winters
Redwing Designs
Specialists in Human Powered Watercraft
http://home.ican.net/~735769/


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