Yes, Salmon, I agree, but actually design has been finalized... I only have the sorta 'winglet' improvement....

BTW these big airliners, b747-400, a340, etc..., use winglets which do not necessarily reduce vortices, but which actually create forward "thrust" (also "side" thrust, but this thrust is not used, this energy is absorbed through mechanical flexibilty) ! Indeed, these winglets are just like 'wings' placed within the airflow coming from under the wing towards the upper part of the wing.

I think this is too hard to implement on models without any wind tunnel, indeed.

I know some people have tried infinite ascpect ratio [sm=bananahead.gif] through annular wings, but that does not help much [&o] ...

To get back to your picture, Montague, that is what I was thinking of... My understanding is that these bits help reducing tip vortices, thus increasing 'useful' upper wing area, and calming down airflow near the aileron tip... It might be just that .