I've seen that article once before. Span is definitely another thing to take into account, and that was kind of implied when the "chart" has been mentioned. Some people think of forward pitch as actually having it forward, but I think it should be thought of relative to the charts.
About that 64 degree angle that was brought up, I believe it's the angle Bill Taylor came up with but I'm not sure exactly how it came about. With a different span and the same pitch or vice versa, the angle changes. It's kind of hard for me to picture, but it's what I was told.
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