HazelNuts39
As discussed earlier, the C* control law doesn't change at low speed, so the SS g rate command doesn't change to a pitch rate command.
Wait a minute, i object.
The pitch command changes gradually from a pure g command in high speed to a pitch rate command in low speed. The changeover point being around 210 Kts. Meaning the SS orders a special amount of g change per amount of SS deflection above 210 kts and blends in pitch rate below that speed, SS ordering a amount of pitch change from existing pitch per amount of SS deflection. That does not change the Nz-law, without outside input the aircraft maintains 1 g flight in low and high speed and is therefore flightpath stable.
HazelNuts39
The THS doesn't move on its own, it is slaved to the elevator. The elevator moves in response to the PF's sidestick, whose 'demand' is interpreted by the flight control law. If there is no demand from the sidestick, the flight control law maintains essentially 1g.
Let me try to be more specific. To maintain 1g flight the computers have to use the elevators in short term and THS trim in long term to counter any speed deviations. That is especially true, when autothrottle is not available and when speed therfore is decreasing or increasing over more than a short turbulence induced period. Like in AF 447 case once placed into the climb, SS neutral would try to maintain 1 g / would try to maintain this climbing flightpath. The speed would decay further and without pilot interaction by either adding enough power or reducing the flightpath significantly with SS ND the aircraft will stall, assumed no protections are available.
In short, the PF commanded the flight path into stall. OTTO disconnected at 02:10:05
True, if you reference that statement to the initial NU SS input after AP disconnect. The timeframe Lyman seems to be questioning and what the discussion turns round since few pages is after stall warning 2, when the THS trim started to move NU. And this movement would have happened also with SS neutral, as in NZ-Law the aircraft tries to maintain that 1 g (tries to maintain the flightpath.
Question remains though, would it have moved in the same timeframe without the help of NU SS input? Was elevator travel already maxed by the task to maintain 1 g without SS input or did the SS NU input aggravate the situation.
Therfore my question concerning the gains.