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Old 16th Oct 2014, 01:02
  #675 (permalink)  
Bpalmer
 
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From RetiredF4:
BPalmer
The airplane is essentially point-and-go. If you pull back on the stick for a few seconds and let go, the airplane pitch will stay there.
This statement is esentially misleading and not completely correct. Correct would be the airplane will maintain a loadfactor of 1g. Correct would be if you add ....... if the autothrottle takes care of the speed. What's the difference some might ask.

Otherwise without the autothrottle (that droppped out at AF447 right at the beginning) the aircraft will decelerate in a climb or accelerate in a descent, and the computers would increase the pitch ( if in a climb) or decrease the pitch (if in a descent) to maintain the one g flightpath.

That mindset "set the pitch and it will stay there (and go there) might have influenced Bonins actions with the SS..
Well, yes, of course —"point and go" wasn't meant as a technically complete description as you must know. But this is still essentially correct and opposite of the behavior one would expect from an airplane that is not essentially neutrally stable.

And you are correct about the need for a pitch change to maintain that trajectory with speed change, and that's what I meant. A conventionally controlled airplane (or one with C*U) will change not only its pitch but also its trajectory to achieve speed stability vs. the Airbus trajectory/g-load stability. This is evident to Airbus pilots when flap settings are changed- the pitch will self adjust to maintain the trajectory/g-load.

But my main point with the "point and go" comment was that if you displace the ss and let go, the pitch is reasonably stable. UNLIKE speed stable aircraft which would in rather short order begin to pitch down for a speed-seeking fugoid.
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