Mr Optimistic
I have no argument with Mr Bernouli.
And as far as I can see I have no argumnet with anything that you have said.
Pressure forces air out of the cone.
Agreed
It is that pressure acting on the cone which propels it away.
Agreed.
But it is an aerodyanmic force acting rearwards so we (usually) call it drag.
In a jet, what ever force that accelerates the air must have a reaction, ie thrust.
Agreed, provided the acceleration is rearward.
For a rocket you integrate the pressure over the internal space, same would work for anything else,
Agreed.
Now let's get back to what I actually said.
Many people believe that the force acting on the nozzle is thrust. They are wrong it is actually drag.
It is made up of friction forces, pressure forces and inertial forces acting on the forward facing (internal) surfaces of the nozzle. But the overall force acting on the nozzle is in a rearward direction.
You are correct in saying that the thrust is the Newton3 reaction to the pressure that is accelerating the air through the nozzle. But this thrust force is not acting on the nozzle.
Now the question becomes, "So if the thrust isn't acting on the nozzle, what is it acting on"?
BRYCEM
I'm not saying that the texts are wrong. Some cover this aspect of the subject and some do not.
I'm saying that many people draw the wrong conclusions from the texts. The majority of people walking away after completing a JAR ATPL Theory course (and a good many other courses) probably think that the force on the propelling nozzle is thrust.
I could of course go and read more books, but my purpose in asking the question is not get an answer. It is to get the readers to think a bit more about the subject.