Originally Posted by
Capn Bloggs
Boeing could have done away with STS by making the aircraft more stable aerodynamically, and we wouldn’t be having this discussion, because it would have been completely transparent to the pilot.
I suspect Boeing won't/can't because more stability more fuel burn means means less efficiency.
I think it's more complicated than that - this is about stability
in response to control movement (which is also why it's off when AP is on). On the R&N Lion Air thread I think there was a post about certification reqs for minimum stick force per knot (of speed change), although I've also seen "stick force per g" elsewhere. As far as I can see the Vessbot's description makes sense, and STS helps meet that cert. req. by
increasing stick force (in effect, trimming against you), in certain phases of flight.
Since you're not pulling directly with cables, I suspect Boeing could have met the requirement by just making the control force larger, but that might have made them too hard to move in other parts of the envelope, where STS is inactive. But I'm not sure, I might have that wrong - my aerodynamics is probably past it's use-by date.