Contributions from A33Z - attaboy
I think all of us here appreciate the inputs from A33Z concerning more detail of the control laws, etc. So ATTABOY!
Some of us are still not clear what is taking place with the "trim", however. My understanding is that the 'bus attempts to achieve one gee ( roll and pitch corrected gear up, not sure when gear and high lift devices deployed). In other words, let go of the stick and the system tries to get to one gee. Pilots can't 'trim" for a gee, only command something other than one gee. So only reason I can see for the THS to move is to allow for dynamic pressure changes ( speed) that limit the elevator's effectiveness and/or allow it to operate from a "neutral" position versus an extreme angle. In other words, the THS doesn't move to achieve anything other than one gee with hands-off stick position. So I can see that as speed decreases or increases, the THS would have to change in order that the pilot gee command would be the same amount of stick displacement, regardless of speed.
Am I close?