A33Zab
Thank you for the useful information of your last post (00:24 Z on 2d). I'd say you have to be very well informed. I mean, it's more than just having a manual lying around. I have some questions-- you wrote:
"The massive THS/Stab for heavy transporters are 'slow' screw driven, therefore the elevators takes the short term pitch orders while long term orders are for THS to neutralize elevator deflection."
My question here is, when CG is full aft, and elevator authority thus at a designed minimum of 1 degree per 1 g, how fast does the "slow" screwjack move the plane of the HS, compared to how fast the movement of the SS moves the elevator through 1 degree?
It seems to me that in any case, the rate at which the screwjack catches up with the elevator is 2-1/2 times faster at full aft CG than it would be at full forward CG. This further seems to me that PF would have only 40% as much times to assess the results of his SS inputs, when CG is full aft, compared to his situation with CG full forward. Am I missing something there?
Beyond that, it is fairly obvious (well, I didn't see it until now, I admit) that 13 degrees NU of the HS jackscrew cannot be reeled off regardless of the speed of the jackscrew, until the A/C has reduced its forward velocity to the point where such angle NU of the HS will not tear the wings off (ie, g < 2.5) (or is there some law where <3.5 would apply?).
It further appears that at some lesser value of degrees NU of HS the A/C is not actually flying, but is so slow that it must stall out. It would seem this angle would be rather readily calcuable. Why did the control computers for trim not make this calculation? Would not air density per altitude probe been the only outside information needed for this? ... together with weight of A/C less fuel burn and fuel in HS, presumably available on board to the computers...)
I admit to asking the question without taking time to see if I am overlooking something obvious. But it would still be better for someone of your familiarity with the THS issue to give an authoritive answer than for I to muddy the waters here by claiming it has to be the way I am seeing it at the moment. Thanks.
Also, in going to 15 degrees NU of the A/C attitude, what is the effect of partial fuel in the hollow HS sloshing to the rear of the HS tank, on aft CG... and then on the above considerations?