PPRuNe Forums - View Single Post - AF 447 Thread No. 10
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Old 30th Aug 2012, 19:02
  #186 (permalink)  
OK465
 
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I think this would lead the system to apply less elevator (to drive the pitch acceleration) than it would normally use at these low speeds,
Agreed.

In other words the initial response would be less rapid but achieving the final desired 'g' not appreciably different.
This doesn't sound right (bolding), but I may not understand what you're getting at.

Amount of elevator deflection for a given SS longitudinal input is essentially the same for 330K in Normal Law, 330K in ALT2(B), and, for example, 200K in ALT2(B), an abnormally low speed for the clean configuration.

At 200K in Normal Law, elevator deflection for the above same SS input is about twice that of the ALT2 deflection.


As a result, I would think you would not ultimately achieve the same peak G value in ALT2 as in Normal, ALT2 value would continuously be lower over the period of the input and never catch up. Holding a less deflected elevator longer isn't going to eventually increase G....and the aircraft response difference would simply be one of the further reduced pitch rate for that speed. Longer time for a given FPA change, which is what a pilot would sense even though the SS 'spring' feel might be associated with different expectations.

My point is couldn't that paragraph in the report just refer to this directly? In the sense that the aircraft is even 'more sluggish' than 'normal sluggishness' at these speeds, I guess truly that is an 'unusual' response dynamic. But given that one is not normally at these speeds clean anyway, I would imagine a pilot assessment of 'unusual' behavior would be a bit superfluous.

Last edited by Jetdriver; 31st Aug 2012 at 00:19.
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