[Paddlewise] More paddle talk - wings and things

I've been thinking about this Toksook vs Big blade vs Greenland paddle
debate.  How can we combine the lift of a Greenland paddle (sweep and
scull) with the drag of a big blade (forward stroke)?    Ever notice the
winglets on the ends of aircraft wings?  The 767s, Airbuses, even the
747-400 have them.  They minimize the vortex coming off the end of a
wing by preventing the flow of air over the end of the wing.  Energy loss
in vortices is like energy loss in wakes in boats - you want to get rid of it.
When I worked as an engineer in an aerospace company, an
aerodynamicist described the winglets as walls that make the air think
it's flowing over a longer wing.  This is like increasing the aspect ratio
without increasing the size of the wing.

Perhaps we could add a "winglet" (bladelet?) to the end of a big
blade and have the water act as if it were a longer, higher aspect
ratio blade.  That way we'd have more efficient lift like a Greenland
style paddle without losing the advantages of the shorter big blade.

Now I thought further of this on Saturday, while competing in a down
river kayak race (in a WW kayak; better than last year I didn't place
last!). This came to me as a local woman hotshot DR racer sped by
me in a carbon and kevlar DR boat weilding a carbon wing paddle at
unreal stroke rates.

The wing paddles are efficient because they combine the drag of a
forward stroke with a lift force on the end of the stroke.  The
wing shape generates lift in the direction of boat motion as the
paddler swings the paddle out from the kayak as it reaches the hips.
Now the wing paddles I've seen all have a turned end - sort of like
a winglet on the end.  Could this be an accidental or planned
attribute to contribute to an effective higher aspect ratio?

Now wing paddles have a dubious reputation when used
for rolling.  This could be because, like Greenland paddles,
they are better fully submerged and most paddlers are used to
having the paddle plane on the surface when sweeping.
Since they're unsymmetric, they don't seem to be ideal for
sculling, since there's probably a lot of difference between
the force generated in stroking one way versus the other.
The curled leading edge would probably generate a lot
of drag on the reverse stroke in sculling as well.  Perhaps a
solid cross section would improve things?

Could some paddle expert speculate on the possible
advantages of creating a blade that has some of the aspects
of a wing blade (including, perhaps, winglets) in designing
a better paddle?

Mike



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