On Jul 16, 11:11*pm, BruceGreeff wrote:

Basically - look at an older design like an ASW20 in a high load
situation the wingtip has substantial vertical displacement. It appears
the wing is flexing to high Angle of attack on the outboard panels.
Possibly this is caused by a combination of the rotational drag force
from winglets as well as the aerodynamic load induced bending.

Evaluating sectional angle of incidence from a photo or video is a
very difficult proposition with many confounding factors. I'd want to
see reference posts secured to the wing before I would try to draw any
conclusions.

The straight leading edge means that the centre of pressure on the wing
remains ahead of the main spar all the way to the wingtip - at high load
this tends to rotate the weakest (torsionally) part of the wing to
higher AoA than desired.

"Center of Pressure" is a rather arbitrary concept mosty used in
elementary aerodynamics and then abandoned. It is more useful to
discuss the forces on a wing section with coefficients of lift and
drag and pitching moment.

On the polyhedral designs the aerofoil and structure is effectively
swept back...

Except, of course, on those polyhedral designs where the wing is swept
forward.

Thanks, Bob K.