OwainG,
Thanks for a truly fascinating analysis, and particularly for expressing it in a manner which we ordinary mortals can understand. In my case, most of it. Could you clarify a couple of points?
(1) Downwash assumptions
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.)
Quote:
The downwash is usually expressed as a value at zero AOA plus a downwash gradient relating downwash and AOA. I have used 1deg and 0.4 if anyone cares.
Is the 0.4 multiplied by the degrees AoA?
(2) Effect of sidestick fore/aft on elevator position (dq)
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.
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.