#2 - Some of the contributrors here may benefit from being reminded that lift & drag are defined as the aerodynamic forces perpendicular & along, respectfully, to the free airsteam, NOT the airframe.
As far as the THS is concerned, with the airplane 'falling' @ ~60deg AOA (e.g) drag would contribute more pitch down moment than lift.
Yiorogos, it seems that if the THS isn't stalled, not important.
If it is, then doesn't that drag force act "up" (a component of the vector, anyway) in a nose pitch down moment, when acting through the arm based on where the CG resides?
I am still left with the picture from my little FBD here that you have forces acting normal to the axis of the aircraft (vector components of vectors acting along the axis you point out) which tend to pitch the nose down, the only component acting against that being the body drag vrom CoG forward to the nose. There's more surface area aft of CG, based on my sketch. Am I missing something here?
Harry, we aren't at a high Mach number if we are stalled, are we?