Re: [Paddlewise] Greenland vs Euro paddles

Nick Schade <nick_at_guillemot-kayaks.com> wrote:

> I frequently here people talk about paddles working like wings and am 
> prepared to accept that it is possible. Yet whenever I ask people to 
> describe how the paddle is working like a wing, their explanations fall 
> flat.

> People like to talk about how Greenland paddles are similar to glider 
> wings etc. But, they never seem to be able to explain how the motion of 
> a forward-stroking Greenland paddle is similar to that of a glider wing 
> through the air.

I agree 100% with Nick, but is not incorrect when Steve Brown wrote:
>High
> aspect ratio wings have high lift-to-drag ratios, which is why they 
> are seen
> on high performance aircraft. Low aspect ratio wings have more lift in 
> when
> stalled so the transition from flying to stalled is less abrupt. This 
> is why
> they are seen on trainer aircraft and aircraft that must operate off 
> short
> fields.

But, the high aspect ratio wing works by having the flow chord-wise,
across the wing at right angles, which hardly is the case with a Greenland
paddle, rather the reverse, as most of the flow on a GP paddle is spanwise,
thus similar to the aerodynamic lift a Sidewinder missile produces from its
body, a lift entirely dependent of vortices - a modern missile can pull 50 G's
in turns, which no high aspect ratio wing ever will be able to, not least to 
their sudden stalls!

So for the vortex system to start you have to push the paddle down and then 
pull backward (same as with a Euro paddle), but due to the GP's extremely
low aspect ratio it eventually produces a more energized vortex, I would 
persume, than the Euro, that has more bite initially, but eventually have 
poorer vortex attachment, due to its shorter blade length.

Oars are pretty much like GP paddles, and the longer the blades the more
efficient I find them, till they get impractically long. And you can, on a 
windless evening, easily see how much longer the vortices remain in 
the water when using better oars! 

I think flutter is the restricting factor when it comes to oars, actually :-)!

Tord
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