Subject: Re: [baidarka] Superiority of Native paddles
From: Michael Daly (michaeldaly@home.com)
Date: Wed Jun 27 2001 - 17:15:57 EDT
Come back from a few days paddling and look what I find:
From: "Peter A. Chopelas" <pac@premier1.net>
> On Wednesday, June 20, 2001 7:59 PM, Michael Daly
> [SMTP:michaeldaly@home.com] wrote:
> >
> > Let's try again. The flow is normal to the paddle power face. The chord is not
> > normal to the flow. You are using the width of the power face instead of the
> > thickness in determining the AR.
>
> This statement is impossible unless the water can flow through the face of
> the paddle.
Peter, both here and on Paddlewise you have adopted the same three
techniques in dealing with others who question your hypotheses:
1 - ridicule their comments (as you've done here)
2 - tell them they're wrong and offer nothing.
3 - call them ignorant morons.
Suffice it to say that until you develop some social skills in a written forum
I'll choose to ignore you.
BTW, before you break your arm patting yourself on the back for being such
an expert:
MD> The AR is the length of the blade divided by the mean thickness.
PC> AR is the span squared divided by area, it reduces to
PC> span divided by cord only in a rectangular platform. [...] (not to be overly
PC> picky but technically YOU are wrong, for most shapes other than a
PC> rectangular one, you will not get true AR with your definition).
1) AR = span * span / area.
2) area = span * mean chord
Substituting:
3) AR = span * span / span * mean chord
or
4) AR = span / mean chord. --- which is independent of shape.
You should have known that, if you were the expert you claim to be.
If you don't believe this is correct, check Marchaj, "Sailing Theory
and Practice" page 65. That's a tad easier to read than most
engineering fluid mechanics texts.
And also the horsepower estimates you've been using are way off.
An elite paddler can produce at most about 0.3 hp for an hour. An
elite cyclist, about 0.5 hp. An average paddler can produce only
about 0.1 hp; some less. If you plug the numbers into those from
Matt Broze's drag calculations and hp calcs for typical kayaks,
you get efficiencies on the order of 25% and up.
Have a nice day.
Mike
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