ORIGINAL: LouW
I think you missed my point. I’m well aware that the test pilot holds the stick rigidly when testing for stick fixed stability. What I’m saying is that the normal pilot likewise generally holds the stick fixed. When he does move it, the motion usually is a corrective motion that contributes positively to the overall system stability. High plain’s statement that the pilot somehow just lets it flop around free is simply not true. There is little difference between the surfaces being held fixed by a servo or a pilot.
(In full-scale airplanes of conventional configuration, the phugoid period is so long that a pilot never lets it develop.)
I must disagree. In measuring stick-fixed stability, (again) the conntrols are held rigidly in place. NO corrections are made, however small. If a pilot is making pitch corrections, we are not talking about stick-fixed stability, and no direct comparison can be made to servos holding the surfaces rigidly in place, as servos and receivers do not by themselves have the ability to make autonomous corrections to deviations from trim, as an on-board pilot (or autopilot) does.