In case of lost speeds, what value of speed is used by the FBW system to transfer a SS command to the appropriate elevator deflection? And does it change again when the speeds are valid again? Was the FBW system using low speed gains during the stall, high speed gains or preset gains (?)
Excellent post and insight into FBW, RetiredF4.
The report states that in ALT2B, pitch gains are fixed for 330 KIAS. Don't have the page ref at my fingertips, but it's in there and it's the only reference I've ever seen to this.
From the simulations I've seen, it appears that the pitch gains are permanently fixed for 330 KIAS regardless of whether the speeds become valid again or not, this as a result of ALT 2B 'latching', and the fact that 'validity' is nothing more than two ADRs being within 25 KIAS.
Though NO two ADRs within 25 KIAS starts a 10 second countdown for display of the ADR Disagree ECAM message....ALT2B with the associated fixed gains 'latches' within a couple of seconds.
Once two ADRs are back within 25 KIAS (doesn't have to be the correct speed), the countdown is terminated and reset (and the FDs return, and no ECAM message if less than 10 seconds). But the gains remain fixed for 330 KIAS. There's a simple way to check this monitoring elevator deflection on the SD Flight Control page.
I'm completely out of the business now, but with respect to all this discussion of simulator post stall behavior and subsequent recovery in a simulator, the last communication I read from a noted sim manufacturer stated that beyond a relatively early point in the sequence, as opposed to 'flying', one is simply operating a high dollar video game.