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Old 13th Sep 2019, 13:21
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OldnGrounded
 
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Originally Posted by DaveReidUK
At the risk of stating the obvious, for any given configuration (stab position, airspeed, AoA, etc) the force required to move the stab (whether supplied by the trim motor or the manual wheel) is a function of the distance between a) a line drawn through the stab pivot point, b) the centre of pressure of the stab and c) its C of G.

The designer's job is to do the sums and work out the optimum position for the pivot.

It's hard to see how moving the pivot way forward or aft of its current location would lead to any significant reduction in trim forces, even if possible from the structural point of view (which it probably isn't).
The location of the pivot point should, however, make a significant difference in the degree to which loading either assists or resists moving the stab away from a particular position. For instance, trimming away from AND with a stab pivoted farther forward would require less force than with a stab pivoted farther back.
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