On Thursday, February 11, 2016 at 8:14:08 AM UTC-6, wrote:
I suspect that the gliders that seem to benefit for slight slip do so for 2 reasons.
First, as mentioned above, is that the slight slip in a glider with a good bit of dihedral will have the force opposing over banking provided without much or any control deflection. Profile drag and spanwise lift distribution benefit a bit.
Second is likely related to wing root separation issues which vary a lot from ship to ship. From my simple observation the gliders with larger well developed root fillets seem to be the ones that are not in the group described as benefiting from notable slipping.
One guys opinion.
UH

I think there is a little more to it. It would be interesting to have wind tunnel data comparing the lift and drag of a complete glider in a pure coordinated 40 degree banked turn at CL max (ball centered, forward mounted yaw string slightly to the outside due to geometry), vs the same glider with enough slip to remove the overbanking force (ailerons neutral, top rudder). My guess is that some gliders will show a small but significant amount of drag due to deflected ailerons (which may be more than the drag of the yawed fuselage and deflected rudder), while others may be less affected.

All I know, it works good on all gliders I've tried it on - from K-21s to my LS6. It may be less of an issue with more modern gliders with smaller wings and less control deflections.

But hey, if you don't believe it, just keep on thermalling with that front mounted yaw string perfectly centered.... ;^)

Kirk
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