Subject: Re: baidarka high aspect ratio paddle blades; lanceolate shapes; drag, inertia and cadence
From: 735769 (735769@ican.net)
Date: Sun Mar 12 2000 - 18:51:12 EST
Phil wrote;
>
> If I understand lift correctly, it is a force generated normal to the
> direction of fluid flows over a body. Drag, on the other hand, is a force
> generated in the same direction as fluid flow. If that's the case, how can
a
> blade's lift characteristics have an effect on performance other than at
> catch and release?
The flow over the paddle varies significantly. Sprint racers (and I) sweep
their paddles to the side to take greater advanatge of lift..
>
> According to a friend of mine who has no interest in paddles but claims to
> have once been an aeronautical engineer, most of the improvement in
> lift/drag with increasing aspect ratio is the result of a lower percentage
> of the total airfoil area being depressurized by flow around the tip. How
> does this apply when flow is normal to the pressure faces rather than
across
> them? In other words, what is the ralationship of drag to aspect ratio
when
> there is no lift, and therefore, no tip circulation?
Your friend is correct in so far as improving the lift/drag ratio is
concerned. In this case the object is to create thrust not reduce drag. One
must apply aero data carefully.
Cheers,
John Winters
Redwing Designs
Web site address, http://home.ican.net/~735769
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