Where is this darn force acting?
I agree with the nice balloon picture and made many an eggshell steam cart as a kid. I was told in my service days that the thrust was felt on all those parts that add energy to the gasses as they transit through the engine. I always have trouble with this when I see a Harrier in the hover as quite frankly the thrust is acting at 90 degrees to those previously mentioned parts. My mental picture now is of the thrust acting on the area of the Nozzle. not the surface but the hole as it were.