Originally Posted by
Machinbird
If the nose had not been prolonged up by the addition of THS trim, it would have fallen through at the stall like most other aircraft.
Do we
know that it's THS or just speculate ?
I don't think the trim goes up much until well into the stall - and by the time it reaches max NU, AOA is already well over 30deg.
What is clear (to me) is that any C* law aircraft will respond to any nose-down stall break with control inputs to counter it - and therefore the pilot may never see the break. I think C*u (i.e. 777) will do the same, but not entirely sure what influence the speed term will have. Once upon a time I might have known how to work it out...
It will, however, respond to the break with elevators, not THS - which will follow slowly on the bus.
Looking at the report, at around 2.11.00, AOA around 10deg, pitch starts to vary and elevator - but sidestick input is all over too, so not clear as to cause/effect. I think they are stalled there though. About 45secs later, elevators and THS hit the stops and suddenly theres a big downward pitch. The stall break finally wins ?
Or, short form, you're right, but it's elevator and THS that stop it - not THS alone.
In Normal law, additional nose up trim is disabled by angle of attack protection:
In Alternate law, it appears that all use of AOA is discarded. No doubt the engineers had their reasons, but I would be real interested in knowing what they were.
I don't
know but I have some thoughts / speculation. For another post, no time right now.