First, thanks to Neil for this great plugin! I've just started to use it and it's great.

Found one peculiar thing though. It's only the distance in the direction of the red axis that will be the wing chord. I installed the plugin and was going to create rib for an old design of mine. The wing was laied out so that the chord of the wing was in the green direction. I could not get any ribs with the plugin and was quite frustrated. Even started with a new drawing and had the same result until I finally tried drawing the foil in the direction of the red axis.

I could not find any notes on this so if anyone else encounters this problem it's documented here. Draw your airfoils in the RED direction!