all planes have this gap Frank. jet engines don't like boundary layer air, especially at higher speeds. this gap between the intake and fuselage takes that boundary layer along the fuselage and directs it around an away from the intake mouth. thus recovering the most amount of energy from the free stream ahead of the intake. if you add the boundary layer to that total, you get a net loss of the free stream total. I've even built this into my 64mm Skyhawk, so I don't injest the boundary layer.
if we use a NACA inlet combination, we won't have to worry about the boundary layer so much, because the inlet will create its own vortex to shed this layer by itself. another win win.