PPRuNe Forums - View Single Post - Gulfstream G650 Crash - Roswell - 4 Dead
View Single Post
Old 4th Apr 2011, 12:00
  #70 (permalink)  
rak64
 
Join Date: Oct 2004
Location: Germany
Posts: 63
Likes: 0
Received 0 Likes on 0 Posts
The pilots performed takeoffs with c.g. locations ranging from 35.0 percent MAC to 42.0 percent MAC. The pilots reported that aft c.g. positions caused them to rotate at a somewhat higher rate. The pilots noted that these effects were more noticeable when they used increased rotation rates (about 6° instead of the normal 3° rotation rate). When increased rotation rates were used, the pilots noted that the stick shaker frequently activated but only briefly. The pilots also indicated that the simulator was controllable at all c.g. locations using both normal and increased rotation rates.
from
NTSB Abstract AAB-04/01

To operate in the transsonic region usually critical airfoils are used. They are known for bad behavior esp. in stall. Airfoils during the desin phasis are tested under sterile conditions. I do not know that airfoils are tested for the rotation phasis.

In a situation just after T/O plus a elevator deflection it is thinkable that the down turning side, defect the aileron down, what increase the average angle of attak, what can cause a partial loss of the airstream attached to the airfoil (stall), what cause reduced lift of that side, known as control reversal.

The only imediate solution i know is to reduce the G-load by moving stick forward. Remember weight is G-load multiply with mass. So the partial stall could not develop to a full one.

As i know simulator are used in aviation industrie using table to look up for the datas, IMHO this kind are not able to simulate dynamic situations. It needs blade technology or CFD to get validate datas.
regards
rak64
rak64 is offline