Thanks. Exactly right.

--- In flapdoodle_dinghy@yahoogroups.com, Darren Bos <bosdg@...> wrote:
>
> This is a bit of a pet peeve of mine and although
> the video is correct, the text could mislead
> some. You don't need a curved airfoil. As you
> can see in the video, they use a symmetrical
> airfoil. Anyone who has seen a plane (with an
> asymmetrical wing profile) fly upside down has
> observed that you can have the airfoil oriented
> in the "wrong" direction and still produce
> lift. So, you could have a theoretical sail set
> tight as a drum, with no curvature and still
> produce lift. The curved shape produces lift
> more efficiently (does so with less
> drag/turbulence), but just about any shape that
> can redirect airflow without creating too much turbulence can produce lift.
>
> Stepping off soapbox
> Darren
>