Why move stab and not adjust column feel to spd stability?
First let me thank downwind for the STS details that show that I had a mistake in my earlier description. I had stated that STS operation was not a function of thrust setting. This is not correct as noted in the details. I will correct my earlier entry to align. In response to Vessbot's comment about why not adjust column feel instead of move the stabilizer to provide missing stick force per knot I see two reasons.
First, if the unaugmented airplane were neutrally speed stable it would not require any steady elevator for a speed change and thus stiffening the column feel would not help as none would be needed to fly faster or slower. Further, if the unaugmented airplane were actually unstable with regard to speed it would require a push force to keep the nose from rising after slowing down and a pull force to keep the nose from falling after speeding up. These are clearly not the desired situation. Stiffening the column feel in that event would actually make the speed stability handling characteristics worse.
Second, if the column feel were stiffened, it would not only change the resulting stick force per knot (the measure of speed stability) but also the stick force per g (a measure of maneuver stability). The problem that STS was introduced to address is limited to speed stability and thus stick force per knot. There was neither need nor desire to change the stick force per g maneuver characteristics. The implementation of STS that moves the stabilizer in the direction to increase speed stability does not impact stick force per knot and thus leaves the maneuver stability characteristics essentially unchanged.