First, thanks for resurrecting this most interesting thread. At one point I thought I was getting this, but clearly I wasn't.
Gornaut states that momentum is being transferred from the supersonic incoming air flow to the engine (and hence to the aircraft). I can't visualize it. Isn't the momentum already in the aircraft?? (It is the aircraft that is moving through the air, not the other way round.)
As I read the discussion, it seems we are getting the ultimate free lunch (which I know isn't right). I'm sure that if we turn off the fuel flow, the net thrust must drop to zero. So how can we say that 63% (or whatever) of the thrust is coming from the inlet duct.
I'm really trying to understand this.