A couple of things ..... the spanwise flow, inboard on inside maneuvers and outboard on outside maneuvers that you see is to be expected. Its an "artifact' or result of the tip vortex strength influencing the overall flow field. Pull a maneuver and the vortex increases in strength and begins to show up on the wing flow.
I do think i can see less stall on the sealed video. I don't know if it was enough that you could feel it..
You are probably correct about the vortex flow driving the spanwise motion. Lighter tufts would help seeing the negative G conditions which I plan on doing. The tip vortex is very clear in the outer tuft. However I still think the flow field along the TE is influenced by the total pressure distribution.
My jury is out on the sealing aspect but there may be some delayed separation. The "stall" isn't really a full stall and more separation on the surface which creates lots of drag. That isn't so noticeable in behavior but in energy on the exit. The take away is that a larger flap deflected less for a given Cl would be less likely to become turbulent thus has less drag and loose less energy.
The plot you have is interesting but 1/32 gap is a lot, mine are more like 0.01" and less on the stab where I can run the hinge pin full length. Honestly that most likely accounts for why I don't see much difference on models. We have to be careful when looking at charts like this one. It's really interesting to see the whole thing but generally we don't operate quite that way, especially on the tail plane. For a given maneuver we fly at a given Cl which on your chart would be moving horizontally between curves which results in just a couple degrees difference in elevator deflection and likely less for a smaller gap. As you say, probably not noticeable but maybe. BTW, what was the source? Nice work.
You can see the wind effect on flow direction over the wing surface. A couple of degrees as you go around the circle. Interesting.
Yeah, probably the most enlightening part of the whole video. Surely not what I would have anticipated but after watching, the "oh, I get it, of course.." falls on your brain. What I find particularly interesting about that is the airplane doesn't seem to yaw much in response. Of course, that is difficult to pick out but this has occupied a lot of my thinking time. I think that this is a practical demonstration of how significant the line placement is and unless the fin is very large the line tension is the dominating factor. Add a test case for the future, move the line around and fly.
The cameras you are using look kinda .... shall we say .. heavy. Have you ever seen a "key fob" camera?
Looks are deceiving. I took the wife's Keyfob out and compared it's larger and almost twice as heavy, 45g vs 27 g. I paid $19.95 for the cameras I'm using which we bought for when we were doing gun shows to monitor our wares as such for my use now they are basically free. We have smaller ones but they required a separate battery and don't have the resolution.
Oh yes ..... you left out the triangles on the second video .... sorry no pattern points1
I did that intentionally to see if anyone was paying attention.
In reality, I am super good at leaving maneuvers out.