Subject: Re: [baidarka] Oscillation Point
From: James Mitchell (baidarka@earthlink.net)
Date: Tue Oct 26 2004 - 16:53:59 EDT
YES, BUT AHEAD OF THE POWER SURFACE!!! I discovered this by accident
when I made a paddle with the power surface set about an inch ahead of
the BACK of the loom. This is so hard to describe. When we are pulling
the paddle forward through the water, our hands are on the BACK of the
loom applying pressure. This is the surface of the loom that is
opposite the power face (ridged) of the paddle.
What I have found is that the amount by which the power surface of the
blade LEADS the back surface of the loom, this amount affects flutter
drastically. If the power surface leads, then your hands are actually
PUSHING the power surface ahead of them. This creates instability. What
if the power surface of the loom led the power surface of the blade?
You will be dragging the blade through the water, eliminating one
source of flutter.
More later. Werner just got here (Starbucks) and is off to order his
latte.
On Oct 13, 2004, at 3:54 PM, William Nettles wrote:
> Based on what Peter and James, other have said, I think maybe flutter
> maybe
> caused by the vortexs on either side of the blade being out of
> balance, or
> oscillating between amounts of vortex-lift and resistance on the two
> edges
> of the paddle.
>
> I'll bet if you could locked a paddle into a vise-such that it couldn't
> twist or flutter and pull it through the water one side would have more
> 'pull' lift' 'vortex' than the other and if this test paddle were
> angled so
> one edge was leading, the forces on the paddle would want to rotate it
> back
> the other way.
>
> This makes me think that if the paddle shaft was some distance behind
> the
> surface of the blade it would dampen the oscillations caused by
> vortexes
> oscialling.
> A paddle like this might not be at all practical of course. This
> imbalance
> of forces, because both sides are 'pulling' increases and has more
> leverage
> with wide Kabloona Paddles.
>
>
>
>> From: James Mitchell <baidarka@earthlink.net>
>> Reply-To: baidarka@paddlewise.net
>> Date: Wed, 13 Oct 2004 10:32:43 +0900
>> To: Baidarka Net <baidarka@paddlewise.net>
>> Cc: Werner Furrer <wmfurrer@earthlink.net>
>> Subject: [baidarka] Oscillation Point
>>
>> This flutter point appears to me to be the water equivalent of
>> breaking
>> some kind of barrier (the sound barrier???). It appears to me to be
>> based on velocity of the water and the shape of the foil. This is what
>> I was referring to yesterday. Peter and Michael, perhaps there is a
>> name for this phenomenon. If there is, I do not know what it is. For
>> now, I will just call it the oscillation point.
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>
James Mitchell
Email: baidarka@earthlink.net
US Mobile Phone: 425-273-0884
15917 Waynita Way NE, E103
Bothell WA 98011 USA
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