Patrick Panzera <panzera@...>
Pat,Wing tips are wing tips, no matter Q or DF.
They will cause drag, but we need them.
I believe the concern here is overall drag (although the subject line says
something different), where as previous DF topics have been on increasing
lift. You choose what you need from your wing tips and design accordingly.
You can design them for lift, and gain some drag. Design them for drag
reduction, and you lose lift.