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Old 11th Apr 2011, 01:44
  #3274 (permalink)  
techgeek
 
Join Date: Apr 2011
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MLG down before impact or not?

bearfoil's post did not explain why lowering the gear might be an attempt to lower the nose. The idea is that the MLG are located below the center of gravity (CG) of the aircraft and lowering them will increase drag with a corresponding change (lower relative to the fuselage centerline) in center of drag relative to CG that acts to lower the nose. I am a software engineer, not an aerodynamic engineer, so someone please correct me if I got this wrong. I know there is also a pitch moment that is the result of the change in position of the center of drag relative to the CG fore and aft (as happens when lowering flaps) and I think that if the MLG are aft of the CG then it would be a pitch up. Please correct me if I got that wrong.

A) this has been done before (with a better result TWA 841 comes to mind) - by the way, my dad flew N840TW after that incident and said it "flew crooked". That incident involved a rate of descent of over 30,000 fpm! That is greater than the rate someone here calculated from the BEA report.
B) if true, this would suggest a desperate attempt by the pilot-in-command to regain pitch control of the aircraft, implying a severe controllability problem.

Of course, a descent into the drink at high vertical velocity already tells us there was a severe controllability problem.

I am curious who thinks this was:

A) a fully developed flat spin

B) a straight ahead "deep" stall

and why two experienced airline pilots couldn't recover from it.
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