This doesn't have anything to do with inherent instability.
There's not enough information around that I can find to give a concrete answer as to what was found under high speed, high bank angle and high AoA as would be tested in a Wind-Up Turn. Some things I've seem mention it's a simple 'stick-force-per-g' test. Other things I've read suggest there was maybe flow separation under these conditions, which would point to accelerated stall.
What we can say is accelerated stalls are stalls that occur at higher airspeeds than the aircraft would otherwise normally stall due to increased g load.
In the specific example I mentioned above, I believe (I can find scant info on this) that additional handling augmentation was required because of the non-linear force on the control column when conducting the wind-up turn. To be certified I believe the 737 Max needed to return a linear force input requirement throughout the entire wind-up turn.
Another comment has pointed out that it is a basic requirement for all aircraft to have this linear feedback curve, so this wasn't just specifically to make the 737 Max handle like other 737 under this particular scenario (though apparently it did evolve to that under other conditions but I'd have to look into that further to be sure).
Again, this is not about inherent instability.
There are some comments out there on the web I've seen that point to there being some issues at slow speeds and high AoA. I'd love to get more info on both things if anyone has it.
But really, we have to use the correct language for the field we are talking about and that means understanding stability/instability are specifically defined and relate to a very specific thing.
>There are some comments out there on the web I've seen that point to there being some issues at slow speeds and high AoA.
1)This is precisely how you induce the accelerated stall I mentioned. Slow down, nose up till you get to the bottom of the energy curve, then accelerate while continuing to nose up. Hold this straight back, or bank to one side, and you stall. It's one of the most basic training procedures there is, although maybe not for 737s.
2) If accelerating causes nose up on it's own (without pulling on the stick) while near the bottom of the energy curve, you could have a run away condition.
So are you saying a run-away condition can still be "stable" in aeronautical engineering terms?
Because I'm pretty sure that's wrong. You might be studying the wrong books re: the technical language.
There's not enough information around that I can find to give a concrete answer as to what was found under high speed, high bank angle and high AoA as would be tested in a Wind-Up Turn. Some things I've seem mention it's a simple 'stick-force-per-g' test. Other things I've read suggest there was maybe flow separation under these conditions, which would point to accelerated stall.
What we can say is accelerated stalls are stalls that occur at higher airspeeds than the aircraft would otherwise normally stall due to increased g load.
In the specific example I mentioned above, I believe (I can find scant info on this) that additional handling augmentation was required because of the non-linear force on the control column when conducting the wind-up turn. To be certified I believe the 737 Max needed to return a linear force input requirement throughout the entire wind-up turn.
Another comment has pointed out that it is a basic requirement for all aircraft to have this linear feedback curve, so this wasn't just specifically to make the 737 Max handle like other 737 under this particular scenario (though apparently it did evolve to that under other conditions but I'd have to look into that further to be sure).
Again, this is not about inherent instability.
There are some comments out there on the web I've seen that point to there being some issues at slow speeds and high AoA. I'd love to get more info on both things if anyone has it.
But really, we have to use the correct language for the field we are talking about and that means understanding stability/instability are specifically defined and relate to a very specific thing.