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Subject: TWL: RE: Alyeska introduction
From: David M. Good (dmgood@XXX.XXX)
Date: Fri Nov 16 2001 - 11:35:54 EST
Richard,
The "fowler flaps" or perhaps more correctly the "flap" design was created
by Keypower in Vancouver, BC. As far as I know, this is the first trawler
application of the concept.
What follows is my opinion, yet to be confirmed by actual operation.
Both the fixed leading portion and the moving portion of the stabilizer have
an airfoil shape. The pivot point is on the forward leading edge of the
moving portion. As the "flap" moves in one direction or the other, lift
will be generated, increasing the effective force of the stabilizer, when
compared to other designs. This lift is produced in the desired direction,
more or less perpendicular to the water flow direction.
Principle benefit should be the ability to produce equivalent forces with
smaller surfaces, or at lower speeds, as well as protection of the movable
surface by the fixed leading edge.
Designs that pivot the moveable surface near the center point, create
undesirable turbulence by the surface that is forward of the pivot point,
and as a result less side forces. Designs that add a bilge keel surrounding
the movable surface further complicate the turbulence situation.
Time will tell but the concept makes sense to me,
Dave
<question>
I am curious about the operation of the Fowler flaps.
I assume the cylinder portion in the picture is forward and that in front of
this is a fixed 'leading edge' portion, and that the actuation involves
controlled deploying of either stbd or port surface of the foil into the
waterstream. I searched the net but did not find a marine application of the
Fowler flap. Perhaps you know of one.
What is the principal benefit over other stabilizer choices?
Richard
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