PPRuNe Forums - View Single Post - AF447 Thread No. 3
View Single Post
Old 3rd June 2011 | 05:53
  #1207 (permalink)  
Machinbird
15 Anniversary
 
Joined: Jul 2009
: ATP+Mil
Posts: 1,587
Likes: 185
From: Not far from a big Lake
MM43
If you go back to Tailspin Turtle's last graphic, it is easy to see that the airflow around the empennage and over the THS will create a turbulent mush over the rudder, making the rudder IMO useless.
It might not be quite that bad. Put 13 degrees of THS leading edge down on that THS and it doesn't block the rudder quite so badly. Also, even past the stall angle of attack, the inboard sections of a swept wing (or THS) are not as badly stalled as the sections further outboard. The VS & rudder being near the centerline should keep them in more energetic flow than it might initially seem.

Thinking about relative effectiveness of the wing and THS, the THS will operate closer to its intended operating point than the wing and thus its C/L should be less affected than the wing's. I.E. With a trimmed up THS (Leading edge down), the THS should become more effective in overpowering the wing pitching moment.
I don't do Aero , so any real Aero's on the thread can comment without hurting my feelings. If correct, that might explain why the stalled aircraft does not want to pitch down. That and the tendency of the center of lift to move forward on a stalled swept wing.
Machinbird is offline