Guppy, you normally write extremely long, readable and informative contributions here, but I can't help feeling you are not fully understanding what this is about. Have you flown 747? What I'm saying is the 747 Alternate or Reserve flaps (I can't properly remember what they were called, it was 4 types ago) have been electrically operated in the air, and medium trim changes occurred due to location of the flaps- they give you an element of pitch control. The electric motors are designed to get the flaps to move slowly, but we are discussing the case when all 4 hydraulics are gone, the control column is waggling back and forwards to no effect, I have carved my way into the roof void and played trapeziums like a monkey on the control runs to no effect (bit of a waste of time that one!), and we are now back in the seat watching awful phugoids expanding each cycle, and we're thinking 'well, better not play with the emergency flap motors because they might burn out?' Why do you not think it would work? Most technically literate 747 pilots have the knowledge that it is available as a last resort.
I currently fly the 747, yes. And no...no 747 has ever been successfully flown, much less landed, following loss of all four hydraulic systems, using the alternate trailing edge flaps.
Why do I think it would not work? You already asked me if I thought it would work, and I replied that I would not speculate. Why do you keep asking the same question? Your question is asked and answered. Move on.
We're thinking
'well, better not play with the emergency flap motors because they might burn out, are we? Doubtful. However, do you suppose the trailing edge alternate flaps, which take 5-6 minutes to run full cycle, are up for flying the airplane with continuous inputs as required, for the duration of the time period necessary to fly to, reach, and operate the airplane on an approach to a landing? Again...it hasn't been done. Perhaps it might work, perhaps not...and certainly one will try everything one can...but to think of it as an alternate means of controlling the airplane following loss of hydraulics would be in error. It's not intended for that, it's not designed for that, it's not a procedure in our manuals for that, or taught for that...it falls more in the same category as a opening the doors in a cessna 150 to effect a turn...it might work, but it's ancillary to the purpose of the control and a coincidence if it does. The alternate flaps control is not an alternate pitch mechanism. The airplane has no reversionary control or electrical ancillary control, and the intended protection is redundancy, not electrical alternate trailing edge flaps.