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On the flip side, I 'spect if one rolled in full nose down manual trim for recovery, one would have a tiger-by-the-tail when and if the stall broke at some 30 or so degrees nose low and accelerating with a limiting 2.5 g available.
Quote Machinbird
Yep, I agree. You would ideally like to dial in a 300 knot trim setting, and only if you absolutely needed it to break a stall would you go to a lower trim setting. But them you better have PNF primed to dial it back pronto as soon as the airspeed begins to accelerate past 200 knots.
Probably better to rock the aircraft out of the stall than to dial in those last few nose down units. More than likely, it would be a quicker and more positive recovery.
Rolling the trim to a normal cruise setting or take off setting initially would aid in the recovery and should cause no harm. The change of trim is not instantaneous and the elevators are still controlled by the Flight computers to achieve the loadfactor commanded by the SS. Hence when the AOA comes down to below stall value and the speed builds up, the trim is in the correct range. Imagine what would happen, if the trim would still be in full nose up position at the point of recovery? By increasing speed it gets more effective and kicks the aircraft back into a secondary stall.
MB, i know what you mean by rocking the aircraft out of stall, but i estimate the success rate of a comercial pilot in doing so very low. Same for extending something to change the airflow. Those are last ditch maneuvers with uncertain outcome. Using the rudder without the dampers active or in a degraded mode and no limiter working might brake off the tail.
In AF447 Bonin was occupied by the bank angle, while a healthy bank angle would have helped him to bring the nose down and get the speed back. Anytime the bank angle was greatest, the nose came down, and anytime he managed to level the wings the nose came up again.
The fast jet drivers in an out of control recovery (Spin is different) know not to deal with aileron or rudder inputs until the nose is below the horizon and the speed is building up, only then it is time to correct the attitude by rolling to the nearest horizon. In a comercial aircraft it might be necessary to control the bank angle within a given limit like 45° or 60°, but i see no point to level the wings as long as the aircraft is still in high AOA. The High AOA is not a bank angle problem, it is a pitch against flight path problem. That is a point where the new stall recovery procedure is not clear about at least not to my sense of thinking.
If all that normal procedural stuff does not work, then it might be the time to go into test pilots territory and try something outside of the procedure.