I'm interested in WW2-era single-engine piston-prop monoplanes. I'm interested in the folding wing mechanisms from the perspective of performance, chiefly two things:
How much extra weight does it add?
How much extra drag does it add?
I did see this pdf about the sto-wing, but the only thing about weight is
The initial STO-Wing design was operated with hydraulic cylinders, but the added weight of the system reduced performance, so a lighter manual system fitted with safety locks was selected for production.
Wikipedia's folding wing article is pretty short, both in words and in data. It did lead to 2 external links.
This article has no numerical data on the sto-wing, but does cite some book: Richard Thruelsen. The Grumman Story. New York: Praeger Publishers Inc., 1976. 125. I was able to find it on Google Books but it looks like you can't search things there like you used to. "Folding Wing" and "Sto-wing" returned very limited results.
The other link is a dead link.
I really hope someone knows where to find these numbers. It would be really nice to see just how much weight goes into this mechanism. To me it seems pretty significant if you're gonna have a strong pin to make sure the wing won't snap-fold in flight, almost like you need another main wing spar in the joint.