Nice explanation KN. I have an aero degree and I know all the science involved with supersonic inlet design, but it often takes model-specific knowledge to be able to say exactly what a design feature does even knowing the science so I generally prefer not to speculate. For example, in this case on the F-4 it is obvious the vertical blade is a boundary layer separator, but I did not know the whole thing moves. If I had known that I might have ventured a guess it changes the cross section area to slow down the air and it might have dawned on me it also relocates the shock a little bit, but model-specific information is needed to be able to say for sure.