So, the Elevator to THS surface ratio is 3:7, which is 1: 2.33. ....
No, the THS area, by definition, includes the elevator area, so the ratio is 3.33:1
But as the THS moves itself, the Elevators move/angle is relative to the THS, and absolute to the a/c body, and thus "complex" - it has two components: its own, and that of the THS.
At this quick writing I am not sure if I am clear.
As the pitching momentum depends on the angle, the complex angle has a complex effect on the pitching momentum.
See my reply to Chris Scott
Imagine cruise AoA, and THS and Elevators at corresponding position.
What would Manual Trim NU of THS do?
WTH do you
think it would do?? The THS would follow the manual input!
It considers only:
max NU, with both THS and Elevators at max NU, and
max ND with both THS and Elevators at max ND,
and leaves out the other two combinations, which are part of the set of possible positions see my original post bellow:
You have the numbers and you can do the arithmetic just as well as I.
question:
are there any other forces (with their respective arms) involved? at that AoA?
Well I did inadvertently leave out the basic wing/body moments. The wing would be giving a ND pitch and the body a variable NU pitch that doesn't get very large until the AOA is around 30 deg. Overall a ND pitch.