RE: [Paddlewise] Greenland Paddles

I would call the force perpendicular to the blade surface "lift"

Sea kayaker had an excellent article a few years ago about how a proper
Greenland stroke kept the blade flying (my word) throughout the stroke by
using a slicing motion that keeps water moving parallel to the blade
surface. I was delighted to find that it was basically the same stroke that
mine had morphed into after using a Greenland paddle for a while.

Anyway, wings stall due to excessive angle of attack. The angle of the
relative wind (or water flow) to the cord of the wing. This is easily felt
on a Greenland paddle by just pulling the blade perpendicular to its surface
through the water. 

Here is a really cool web page about angle of attack, including a simulator:
http://www.lerc.nasa.gov/WWW/K-12/airplane/incline.html

A Greenland paddle is essentially a symmetrical wing which is not known for
delayed stall. Fat bladed euro paddles not only have better lift in stall
due to their low aspect ratio, but the much more exaggerated asymmetrical
wing shape which keeps water flowing parallel to the "wing" surface at
higher angles of attack - thus delaying stall.

That same shape is used on STOL (short takeoff and landing) aircraft. Here
are a few web pages that shows the use of leading and trailing edge flaps to
achieve the same shape and effect--->

The last flap example on this page really looks like a paddle:
http://www.allstar.fiu.edu/aero/Wing33.htm

Figure 2 on this pages shows why a euro paddle works so much better than an
Greenland when just pulled through the water:
http://www.zenithair.com/stolch801/design/design.html

Moveable surfaces are used for airplanes so as to have minimal drag
consequences with flaps retracted at cruising speeds when high angles of
attack are not required. The kayak analogy is to use a euro paddle for
punching out through the surf, then to pull your Greenland paddle off the
deck for cruising.

Anyway, no surprise that the "wing" paddle has the most exaggerated
asymmetrical wing shape of all.

Paddles are wings

Steve Brown
 

-----Original Message-----
Obviously the blade produces a force that has a forward direction, 
otherwise the boat would not move forward. This does not mean that any 
of that force is produced by lift. It could just as easily be produced 
by drag. ........

Nick Schade
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