AoA versus Gee, once again
Salute!
Decent explanation of the trim, OK.
OTOH, I don't think Retired thot the trim had anything to do with rates. And he can jump in here to clarify.
It is true that the trim acts to reduce the pilot input to maintain either an AoA ( older planes) or a gee ( at least two FBW systems I am familiar with). And the amount of elevator deflection or THS position will be adjusted accordingly. Am I good so far?
So am I off-base assuming that a constant gee command of, say 1.15 gee for a 30 deg bank turn with none of the "normal" laws in effect, would result in the THS gradually trimming to reduce the pilot's requirement to hold a bit of back stick?
Sounds fine to this old dinosaur.
But then I note that AoA protections ( I prefer "limits") are lost in ALT laws when there are problems with the ADR subsytems. So I can understand trimming by the system or manually by the pilot that could result in the jet exceeding the stall AoA.
I look at the Airbus protections and laws and am impressed by how many are related to attitude versus AoA or even gee. The pterodactyl FBW system I flew 15 years before the A320 was AoA dominant. At low AoA you could get to 9 gees, but as "q" decreased, you hit the AoA limit and the gee available reduced until it was one gee, So at 25 deg AoA we flew at one gee with stick all the way back, regardless of our trimmed gee. And I point out that we trimmed manually for gee using the collie hat or the trim wheel. So we could trim for zero gee and if we let go of the stick the jet would try to achieve zero gee ( neat feature to gain energy, called unloading). Our trim limits were about - 1.4 gee and + 3.4 gee. The Airbus doesn't work this way.
As far as the THS contributing to the prolonged stall? I would think it hurt, but was not the primary factor. As Doze discovered in the sim, the elevators had sufficient authority to get the nose down.
I strongly disagree with the loss of AoA "protections" when airspeed is FUBAR. If the initial pilots did not complain about the 60 knot value or even unreliable speed values, I understand. OTOH, I cannot understand why the "q" was not augmented by a simple WoW switch. After all, the jet is in "direct law" until liftoff, isn't it? And then switches to "normal" law. Or am I mis-reading the FCOM's and other manuals I now have courtesy of several here?
Lastly, and for those who have not flown to the limits and beyond... If the wing camber does not have a decent washout, then the wing stall will progress from outboard to inboard. This results in movement of the center of pressure forward and actually reduces dynamic stability more than static stability. Hence, it becomes harder to get the nose down. It also reduces aileron/spoiler effectiveness.
too much verbiage, and remember that I started as a dinosaur and then evolved into a bird, heh heh.