Old 13th Jun 2010, 18:11
  #23 (permalink)  
PBL
 
Join Date: Sep 2000
Location: Bielefeld, Germany
Posts: 955
I find it hard to believe that anyone with an understanding of aerodynamics would disagree with anything I said, but it seems to have happened. Sorry.

If there is a pusher, the pusher will kick in at a determined point. You can take that, if you like, to be a definition of "stall", namely the point at which the engineers decided the pusher should activate. It is not necessarily the same thing as CLmax, as Mansfield suggested it was.

Mansfield also quotes the certification regulations, to show that flight tests are performed at various combinations of parameters to a defined point of stall. Well, yes indeed. Those have all been done during certification of the airplanes we are talking about.

So what data is it that a given manufacturer didn't have, that they would have gone back up to get because the regulators were worried again about LOC? Can anybody here say?

On to semantics. If an airplane is equipped with a stick pusher, then, granted if you will, a stick pusher activates at the point of defined "stall". That is, you get slower and slower, up to a specific airspeed at which stick pusher activates, and over you go. At what point in that entire process can you be said to be "stalled"? A suggestion: at no point, or maybe at just one. So, if I may be permitted to insist on accuracy, you are performing a manoeuvre which can be best described as recovery from approach to stall, not as recovery from a stalled state. The pusher does not let you get into a stalled state. Isn't this obvious?

An analogy. You walk up to the edge of a lake with shallow banks. You let your shoes go right up to the edge of the water. The water touches the very tips of your shoes, but no more. Are you in the lake? Are you wet? Have you been wetted? If you step back, are you recovering yourself to dry land from being in the lake? Answer as you will. I would say, you went up to the edge of the lake but you didn't recover from being in it. Similarly with a stick pusher and stall. You went up to the point of stall but you're not recovering a stall.

I am happy to agree that the current action is a general response to recent LOC accidents if that wording seems more appropriate to some.

PBL
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