Originally Posted by SCaro
The stall originates at the stall strips, which are about 30 inches outboard from the fuselage.
.....
I tried different angles of stall strips, that did not change stall speed.
together, those two statements are VERY suspicious.
If I understand you, the stall on this model is supposed to originate from the stall strips, YET on this specific tail number the stall speed did not react to the position of the stall strips. This implies that the stall is actually being triggered by a mechanism independent of the stall strips for this aircraft.
How far did you move the stall strips, and in which sense? If you moved them further down (under) the leading edge, which would correspond to a higher stall AoA than normal, hoping to delay the stall and get a lower speed, and nothing actually happened, this would be consistent with the theory that something else is tripping the flow.
That something is, I'm afraid, quite possibly your deformed LE profile.
If you wanted to try a test to confirm the theory (albeit not really solve anything...) you could calculate the delta stall strip position consistent with a 3 degree ADVANCED AoA, and place the strip in front of this position. This should then cause a change in stall AoA as the strip finally gets a chance to work before the other unidentified trip mechanism takes effect.
That would confirm the behaviour, it won't FIX anything. I fear you may be looking at further work on the LE - perhaps even reskinning, although I know thats an ugly word.