Dave,

Sorry I don't know the aerodynamics (was trained in fluid dynamics of
bioreactors, not aerodynamics) only that it made a world of difference
on both my Nimbus 2 and Ventus B. The wings will drop on both without
it, where with it I can usually come to a full stop before the wing
will drop. It is definitely not a placebo. Try it in an 8-10 knot
breeze. Point the plane into the wind and try both positions.

Tim