Klein-Fogelman... I have their book.
Perhaps the "America's Cup" guys might look at it.
Basically it's nothing more than trying to push a sailboat with a fan attached to the sail boat blowing into the sail.
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Several years ago my nephew got me interested in the thing. I built a wing for a Goldberg Mirage using a 23012 with K-F step on the bottom.
One of the best wings I've built.
I still have it, thinking of covering over the step to make a real wing out of it.
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Flying exhibited no unusual characteristics such as faster/less fuel needed.
With all the negative results K-F eventually decided it was a "safe" airfoil. Difficult to stall or something like that. As it required more power than a conventional wing to operate, and would therefore be less efficient, I think the aviation community yawned at the idea.