Originally Posted by
Lost
If you were to pitch the aircraft over and increase airspeed, the stab generates more down force and restores things back to where they were, after a few oscillations. That is dynamic stability. Works the other way also. Slow down, and some of that restoring torque attenuates, the nose drops, and goes back to "trim" speed. Nothing new here. All tried and true.
Now, go and re-arrange things and make the stab carry some of the lift function, and dynamic stability goes away. That is why we would have a wild (fatal) ride if we load much past the rear CG limit. Increase airspeed, and you get even more lift in the tail, and the nose pushes even further towards the houses.
The first part of the above quote stands to reason, the second part you need to rethink, I think.
Picture a lifting tail, with a positive angle of attack in level cruise flight at say 150 KIAS. Now push the nose forward and retrim to 170 KIAS. How has the tail's angle of attack to the relative wind changed? Its less. Less angle of attack means less lift, more or less.
In the other thread you asked what, in my Caravan world view, happens to the tail airflow when tail aerodynamic forces shift from down to up? I think under the wrong conditions (too slow) the airflow over the tail fails to provide the required up lift when called for and the plane falls out of the sky. That, I posit, is why conventional aircraft design employs downforce only on the tail.
The most important thing to take away from all this is what 185flier already wrote. If you are retracting flaps in the Caravan and weird things happen, put them back to where they were when the plane was still flying agreeably.