PPRuNe Forums - View Single Post - AF 447 Thread No. 10
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Old 7th Mar 2013, 22:58
  #899 (permalink)  
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Join Date: Jun 2009
Location: florida
Age: 81
Posts: 1,610
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Hey, Lyman!

OG, Nuts, PJ and Cland are onto something.

1) Although phugoid mode exists for normal planes, the FBW systems negate it. They are contantly attempting to maintain an attitude or gee. The bus mixes both.

2) Cland mentioned the turbulence a few posts ago. Right on! At low altitude over the desert, with all the thermals and such, our little jet felt like a 757 or something. The system reacted to the up and down quicker than we could - very smooth ride.

3) Only FBW system I know of that uses AoA for trim is the Viper when the gear is down. The 'bus uses pitch attitude a lot more than we did ( we used it ZERO!!!). Could be the Hornet and Raptor and Lightning and Tiffie have a similar control law with gear down. But I an't find any AoA bias for the 'bus unless the sucker is about to get into a stall.

We may discuss the fine points about the control laws and the implementation, but the cause of the crash was a crew problem. Some misunderstanding about the finer points about the control laws may have added to the confusion, but just that.

And thats what this pioneer in FBW jets has to say.
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