PPRuNe Forums - View Single Post - AF 447 Thread No. 5
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Old 14th July 2011 | 00:19
  #278 (permalink)  
takata
 
Joined: Jun 2009
Posts: 691
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From: Paris
Hi gums,

It is nice to read that you are still with us.
Originally Posted by gums
- Although the pitch moment chart I posted is for another aircraft, it illustrates two points ( one positive, one negative) that result in little or no pitch control authority for the existing HS/elevators/stabilators in either positive or negative direction.
I've got a question for you about pitch.
We know from BEA that AF447 had a MAC set at 29%, but also an optimum target that would be closer to 39% MAC, both being inside the safe certification limits. Now, people here tend to agree that, for an attempt to recover from a developed stall, having an aft CG would be a real issue.

Unless I'm mistaken, would not a further aft CG provide a better elevator authority (at least sensitivity)?
I seem to remember that moving the CG forward is a trade off for elevator sensitivity. Hence, in case of stall recovery, may be it is better to have more elevator control with a CG further aft, at least until the point that it is still inside the safe envelope.
What would you think preferable, in this case, 29% or 39% MAC?

Last edited by takata; 14th July 2011 at 00:34.
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