PPRuNe Forums - View Single Post - AF 447 Thread No. 5
View Single Post
Old 25th July 2011 | 01:44
  #644 (permalink)  
Machinbird
15 Anniversary
 
Joined: Jul 2009
: ATP+Mil
Posts: 1,587
Likes: 185
From: Not far from a big Lake
Dutch M
The implications of the above, is that, in case the aerodynamics is
different as expected, the airplane can be stalled, without the
stall warning being triggered.
HN39 has done an energy matching simulation (segment by segment) combined with aerodynamic assumptions. (Believe it was in the prior Tech thread.) His conclusion was that the final climb from FL375 to FL 380 was ballistic, i.e. the aircraft started upward on the last dregs of its lift and decelerated below actual level flight stall speed in the climb. This would allow the aircraft to fly below actual level flight stall speed and continue trimming nose up because the AOA had not yet become high enough to shut down the automatic pitch trimming. When gravity caught up with the aircraft and it began to fall, it then went rapidly well past the stall AOA and shut down the automatic pitch trim at 13 degrees ANU.

HN39 is very good with this type of thing, and we Physics duffers should respect his knowledge.

HN39, if I have gilded the Lilly too badly please correct me.
Machinbird is offline