Earlier,

Richard Riley wrote:

These guys selling snake oil too?

http://www.star-tech-inc.com/papers/aiaa/aiaa.pdf

http://tinyurl.com/g66ln

http://jeb.biologists.org/cgi/reprin...lcode=je xbio
...

Not at all. They make a convincing case that carefully-implemented
multiple element winglets can reduce induced drag so as to improve best
L/D over some range of Cls, especially for wings with low aspect ratio.
What they don't try to do is sell such configurations as a panacea, a
"substitute for span."

As all good sailplane pilots know, the only substitute for span is
talent. The difference between the two is that you can _buy_ span.

Thanks, Bob K.