Quote:
THS AOA is just the body AOA less downwash and THS setting.
Should that read "... body AoA LESS downwash PLUS the THS setting? (Given that the THS angle is negative.)
Yes, sorry for any confusion.
Is the 0.4 multiplied by the degrees AoA?
Again yes.
Can you confirm that, with stick neutral in the descent phase, Pitch Alt law would still have provided substantial up-elevator (i.e., a minus dq)? Any idea how much forward stick would have been required to neutralise the elevator? I also wonder how much down-elevator could have been achieved by full forward stick, and if that might have been enough to stall the THS.
I think so. As I understand it, with neutral stick the system would have tried to maintain the 'g' present at the time the stick was neutralised, on the assumption that the pilot was satisfied with the situation at that time. Trouble is that there were periods of time (02:11:06 to 02:12:06 for example) where the 'g' was less than 1.0 but quite a lot of up elevator was being applied (and presumably needed). Since stick movement even in Alternate is a 'g' command not a direct elevator command I don't see how to easily translate that into how much stick would neutralise the elevator. Given though that even in the worst case that the THS AOA was only 9 or 10 deg I don't think that full down elevator would have stalled the THS.
You make a particularly significant point when you state that, elevator authority being two-thirds as much as THS, stopping the THS running beyond (say) minus-3 would probably not have made any difference until the AoA reached +35.
I didn't think I said that in quite that way, but yes, I agree
