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I think it all started with the belief that the lower wing was less efficient, due to upper wing interference, than it actually was. Best to put the wing area in the upper wing and minimize the lower. The biplane configuration was a given due to bracing requirements. A smaller lower wing would also improve visibility downward. What was unknown, and unanticipated, at the time was aerodynamic flutter. The heavily under cambered and lightly built lower wing on the Albatros was particularly prone to flutter. The strong lift vector in front of the spar at high speed forced the leading edge up; material strength resisted the movement and brought the leading edge back down. This up-down sequence happened VERY fast. I would guess the last thing many Nieuport and Albatros pilots probably heard was a low-pitch buzz from one or the other lower wing tip and BAM the wing fails and that's all she wrote.
I also think the effect of rigging on drag is not as great as generally supposed. It was well known at the time that in order to attain the required structural strength a thick wing section was needed to contain a deep enough spar (or spars) to handle the loads. A wing thick enough to obtain the required strength also generated as much, and probably more, drag than a thin wire-braced wing. What seems to be unappreciated at the time was the much gentler stall characteristics of a thick wing with a relatively blunt leading edge. This is one of the major things that gave the Dr.I and D.VII their edge in combat. Pfalz tried fully rigged and “wireless” wings on one of their experimental fighters in 1918 and found no appreciable difference. I also think the British rigged a captured D.VII to see what effect the wires had and came to the same conclusion. Witness all the thin rigged wings post war.
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