PPRuNe Forums - View Single Post - AF 447 Thread No. 9
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Old 16th Aug 2012, 01:23
  #1327 (permalink)  
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Join Date: Jun 2009
Location: florida
Age: 81
Posts: 1,610
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First, I have to thank the FBW system we had in the Viper when the LEF folded up just after gear was up. With no input from me the system tried to achieve zero roll rate. Wasn't enough and I added more left stick to stay level. Any airplane at the time would have gone to an uncontrollable right roll and I would have had to pull the handle real quick. So I had a pound or two of roll authority to left, and I then held speed from increasing as I worked out things. Nothing in the books and we didn't even have a simulator yet. I did use the rudder trim to keep the pointy end forward, and I pulled back power to stay at a speed that had allowed me some control. Was I a Chuck Yeager? Well, in that jet at that time we were all "test pilots". We flew more hours in less time than the 5 or 6 years of development, and we had basic hamburgers like me doing things the engineers never thot of.

Tex has it right about THS implementation. Make this clear - I have no problem with the auto trim functionality of the Bus THS. I have no problem with the feature even in any sub-law except "direct". Our auto trim was always back to a trimmed gee that we could set ( can't do that in the Bus). Attitude corrections for the gee trim were not a player, either.

I also agree with a few here, that in "direct" law the inherent static stability of the Bus might have helped. In other words, to maintain an attitide you would have to push/pull and the plane would try to achieve some AoA based on cee gee and its basic pitch moment capability of the elevator/THS. Then you trim the sucker. Why this guy thot that 10 or 15 degrees of nose up attitude was acceptable is a mystery. Even in a high-performance jet fighter, those numbers were unacceptable for basic IFR or even VFR cruise. Hell, two or three degrees was about all I ever expected in mild turbulence.

Last edited by Jetdriver; 16th Aug 2012 at 11:11.
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