RE: [Paddlewise] Clarification?

Skepticism is healthy.

Use a sculling brace to prove your paddle is a wing that can stall.

When a wing is flying, increasing AOA increases lift. A stall is when
increasing AOA does not increase lift. Continuing to increase it beyond that
critical AOA will actually decrease lift. Drag, however, continues to
increase with AOA. The AOA at which a wing stalls does not change with air
speed, or the weight on the wing. Airspeed effects the lift a wing produces
for a given AOA and the weight on the wing determines how much lift is
required to keep it aloft..

The procedure for stall recovery in an airplane is to put the nose down
(reduce angle of attack), use gravity (and full power) to regain airspeed
(increase lift) so that the weight of the airplane can again be carried
without exceeding the maximum AOA, and then level out.

With a kayak paddle, a stall is most easily experienced when bracing. The
procedure for stall recovery during a paddle brace is sculling. Effectively
reducing the AOA, and regaining water speed across the blade so that
adequate lift can be maintained without again exceeding the maximum
acceptable angle of attack.

Many, if not all on this list can easily manipulate their paddle during a
sculling brace to prevent it from stalling. Too much AOA and you start
kicking up tons of water (increased drag), but you still continue to sink
(loss of lift). As you slow or speed up sculling, you will intuitively (once
practiced) increase or decrease the AOA to maintain the lift necessary for
the brace.

I know what a wing stall feels like, because I've done it in an airplane. On
the other hand, I can't prove that it was a stall because I didn't
specifically measure airflow separation. On the other hand (that's three
hands), the stall horn was blaring, the nose dropped, and it had all the
symptoms of dramatic reduction in the lift-to-drag ratio. Same with a paddle
brace (except the stall horn)

I think most who have paddled with a Greenland paddle can feel the effect.
If the angle of attack gets too high, the blade dramatically loses lift
(thrust, or whatever the term should be in a kayak). That is why the stroke
always morphs into one that keeps the blade flying. I will not insist that I
keep the blade from stalling entirely during a forward stroke, because
stalled wings do produce lift, but I am sure that I am keeping it from going
too deeply into a stall, and possibly keep it out of stall for most of the
stroke.  The effect of stalling (or deep stall) for a forward stroke would
be reduced efficiency, which is much more subtle than a failed brace. It
took me a while to learn not to just yank the blade back through the water,
and I'm not sure if I ever really mastered it to full efficiency (probably
didn't)

Have I proven that this is a stall? No, but it has all the same symptoms as
a wing stall so I'm content assuming that it is one in the absence of
conflicting information (which I am open to if shared).

Steve Brown
 

-----Original Message-----
....

Do you have any tests that prove you can 1. detect stall and discern it from

any other forces acting on the paddle and 2. Adjust the angle of attack 
rapidly enough to make a difference? By this I mean tests I can perform to 
verify or refute your claim.

.....

Cheers

John Winters. 
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