I've done advanced physics, but this makes no sense:
"Alternatively, if the aircraft maintains the same speed and climbs, the balancing force is a greater aftward component of weight, at the centre of mass."
Look at difference in the equilibrium of forces before and after the thrust increase. If the aircraft has maintained the same speed and is climbing after the thrust increase, the major differences between before and after are:
1) The difference between thrust before and after due to the thrust increase
2) The difference in aftward component of weight before and after due to the change in flight path
The differential forces will be of approximately equal magnitude. If those two forces are offset so as to produce a couple, there will be a pitching tendency. in that case, the centre of drag is irrelevant.
It's not a question of looking for questions, the answer lies in providing answers. How's your morale now?
