wing flapping

Does wing flapping like bird in a thermal improve the glide ratio?
The answer is no, as you can see below.

To a first approximation, the reason is that during flapping, the wing AoA moves around the « steady » polar and the result is simply the average. It would appear that there is no favorable dynamic effect.

Please note that during this flapping, the wing does not approach the stall, as can sometimes be done to severely degrade glide ratio.