At any angle of attack other than zero, a flat surface may have flow separation on the low pressure side, shedding vortices and inducing drag. This is what is known as "stall angle". The foil shape maintains laminar flow over the foil at the greatest possible range of angles of attack, preventing flow separation until the angle of attack is much greater than could be accomplished with a flat control surface, and also minimizing drag in the process.
-Sean
On Sep 13, 2009, Jon Wallace <jonw@psubs.org> wrote:
Jay,
I looked at the images and the chord appears to be symmetrical which
raises a couple of questions assuming it is intended as such and I just
can't see enough detail from the photo. What is the advantage of
fabricating a chord as opposed to a simple flat surface if lift
(positive or negative) is not required or being introduced.
Jon
Jay K. Jeffries wrote:
>
> Here is the link to 5 images that depict a NACA 65-020 high aspect
> ratio fin and screen captures from my foil development software:
> http://www.flickr.com/photos/bottomgun/sets/72157622232798965/
>
>
>
> Let me know if you cannot see this link.
>
> R/Jay
>
>
>
>
>
> Resepectfully,
>
> Jay K. Jeffries
>
> Andros Is., Bahamas
>
>
>
> *Save the whales, collect the whole set.*
>
>
>
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