Oh yeah! Just watched the videos - way better flow! No surprise, right??
Also saw an interesting change in the
direction of flow near the edge of the bottom, about half way down the length of the tail.
Before adding the undertray, the flow seemed to be wrapping down from the side towards underneath (going aft at about a 45 degree angle), and now it appears to be flowing from the bottom toward the side.
Suggests the undertray has increased pressure beneath the tail higher than it is on the lower left side, where the reverse was true without the tray.
I'll make a diagram or screen cap to show it best. Which is coming, eventually.