@OK465
This doesn't sound right (bolding), but I may not understand what you're getting at.
I'm not sure if I can explain it easily, but essentially what I am saying is that the time to achieve the desired level of steady state 'g' will not be
radically different whether the C* gains are high speed or low speed values. What will be different is the time history of how you get to that state.
Amount of elevator deflection for a given SS longitudinal input is essentially the same for 330K in Normal Law, 330K in ALT2(B), and, for example, 200K in ALT2(B), an abnormally low speed for the clean configuration.
At 200K in Normal Law, elevator deflection for the above same SS input is about twice that of the ALT2 deflection.
With C* operative you cannot simply relate SS movement and elevator deflection in any dynamic sense. What is true is that for any given set of weight/CG/speed conditions the SS movement, elevator deflection and
steady state load factor are uniquely related and independent of whether it is normal or alternate law in operation. In other words the steady state elevator angle/g required is independent of C*.
What does change with C* law changes is how the elevators are moved between initial and final states. Suppose one has an aft CG condition where the steady state elevator angle/g is only say 2 degrees/g and you want an increment of 0.25g (these are just for instance numbers OK?). If you just apply 0.5 degree elevator you will eventually arrive at the new trimmed state, but 0.5 degree elevator isn't going to set the world alight in terms of pitch acceleration, so it will take a long time to get there.
To avoid this C* does what I think pilots would do instinctively in these circumstances - overdrive the elevators to get the aircraft moving and then back off to avoid any excessive overswing [correct me if I am wrong] and let the aircraft come gently to the final trimmed state.
In normal law, or alternate law with standard gains the aircraft response would be a fairly rapid g response, followed by a modest overswing and a damped recovery to the desired steady state g. I suggested that this whole process would take about 6 seconds, but that was a notional value and could be anything form 4 to 7 secs depending on aircraft.
In Alt2B with the default gains the elevator overdrive would be less, the initial pitch acceleration would follow that and there would be no overswing, just a gradual build up of 'g' to the final value. From reports I have read where C* gains have been varied (on large aircraft) this
final state is arrived at in about the same time as with the 'normal' laws. The pilot's perception of the dynamic response however would be very different.
In this respect I agree that the dynamic elevator deflection in normal law could be twice what it is in Alt2B.
As a result, I would think you would not ultimately achieve the same peak G value in ALT2 as in Normal, ALT2 value would continuously be lower over the period of the input and never catch up. Holding a less deflected elevator longer isn't going to eventually increase G....and the aircraft response difference would simply be one of the further reduced pitch rate for that speed. Longer time for a given FPA change, which is what a pilot would sense even though the SS 'spring' feel might be associated with different expectations.
For the reasons given above I can't agree that the 'g' in Alt2B will never catch up or that holding a less deflected elevator longer won't eventually increase 'g'. There would be a slightly longer time for a given FPA change, but (question) does the pilot "see" FPA change first as a 'g'?
My point is couldn't that paragraph in the report just refer to this directly? In the sense that the aircraft is even 'more sluggish' than 'normal sluggishness' at these speeds, I guess truly that is an 'unusual' response dynamic. But given that one is not normally at these speeds clean anyway, I would imagine a pilot assessment of 'unusual' behavior would be a bit superfluous
Agreed