Would a triplane be way more efficient if the wing tips were joined at the tips to create one wing tip vortex instead of 3, at RE 200-600k? At that low of a speed, I assume interference and form drag are minimal.
I understand biplanes and triplanes are less efficient than a monoplane due to wing root interference drag and wing tip vortices.
Yet..... I understand boeing/NASA are experimenting with a biplane/braced wing airliner configuration, which would have extra induced/inference drag.
So, to reduce those nasty wingtip vortices, couldn't one just intersect the tips?
I'm thinking, the top wing would have anhedral, a straight middle wing, and bottom wing with dihedral, meeting at the tips.