Low Dihedral, Polyhedral (gliders)
Re gliders,
1) What is the benefit of a low, or no, dihedral wing, given its generally greater tendency for spiral instability and tip stalling in turns >> Aero efficiency? Some other controllability issue?
2) Are polyhedral wings used mainly for their greater roll stability and turning ability, or is there actually some L/D benefit, at least to offset the added interference drag?
I believe it was Bob Dodgson (of Dodgson Designs) who was a proponent of DIHEDRAL thermal designs over polyhedral, for reasons I don't recall.