Navvie wrote:

From: http://www.djaerotech.com/dj_askjd/d.../wingfin1.html

This is from a model airplane web site, and some of the terminology for
hydrodynamics is rather different. For one thing, we don't talk about the
"helix angle" of underwater foils. For another, attempting to get a net
forward (or windward) lift component from keel winglets isn't going to work
because they have to sail on both tacks.

If an airplane were designed to spend 50% of it's time flying upside down,
you'd see some very different wing section and winglet designs... in fact, you
can look at some stunt plane designs and see...

Fresh Breezes- Doug King