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Old 18th Feb 2014, 16:54
  #493 (permalink)  
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Join Date: Jun 2009
Location: florida
Age: 81
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TNX for the reference. I agree, hard to accurately interpret, but look like the duplication follows the actual parameters well. So the crash was inevitable, huh?

Secondly:
"...the jet maintains a one gee Nz " command" corrected for attitude if the stick is in neutral ( hands off)."

In Normal Law, yes (also compensated for bank, BTW). But we are discussing Alpha-Protection mode here. The EFCS targets an AoA of alpha-prot with neutral stick, and alpha-max with the stick fully aft. Nz doesn't rule.
From looking at the FCOM stuff you folks provided two years ago, it looks like the "alpha prot" and such is simply the far right of the control law for pitch. In other words, AoA is blended into the Nz commands, and that resembles the law I had in the Viper. We could command 9 friggin' gees but the system would not let you get above a certain AoA versus gee. By the time you reached max AoA, all you could get was one gee positive Nz ( negative still available).

I don't see the alpha prot as an "alternate law" as such. Secondly, if not pulling, I can see why the system would continue to operate in an "alpha" mode unless speed was so slow and power reduced so much that the jet would stay there until thrust was increased ( and speed). Am I understanding that? Of course, with altitude, we could avoid that by rolling and getting the nose down while still holding full back stick ( not recommended for a large jet, heh heh).

Lastly, your description may explain some of what we saw with AF447. Once slow enough, pulling back on the stick would not help, although nose down authority was still available.
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