Originally Posted by Keith.Williams
Many people believe that the force acting on the nozzle is thrust. They are wrong it is actually drag.
Some people first define what they're talking about. A con-di nozzle above Mach 1 usually produces at least some of the thrust.
On Concorde (like the SR-71 quoted earlier) most of he thrust came from... yes, the intakes.
On the SR-71, above Mach 3 under certain circumstances, the engine itself actually produced drag, evidenced by it moving backwards on the suspension points.
CJ