PPRuNe Forums - View Single Post - AF 447 Thread No. 6
View Single Post
Old 21st Aug 2011, 06:28
  #234 (permalink)  
Lyman
 
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes on 0 Posts
So I considered just allowing a slag off of my opinion, but I think it a good question, and will pose it once more.

Per the post by airtren of the THS and Elevator traces, I notice a dormant THS, positioned at 3 degrees virtually the entire time of the climb. It then travels to 13.6 degrees Nose Up at a very consistent rate at and during the STALL WARN.

STALL Protection is lost in ALTERNATE LAW, but 'g' protection remains. The elevators work via the FCS, and respond to load, or g sense.

So Pitch is not DIRECT, and it is independent of an "active" (variable) Stick. No excessive elevator deflection to be expected. The climb shows a response to NU input, again, without TRIMMING, which is ACTIVE in this LAW.

Why then, no "compensation" for the elevator position? The stick is held back sufficiently to command autotrim, but none shows.

Why? Because the THS, its Autotrim function, is inhibited in the region above 1.25 g, and below .75 g. The g traces show that the g is consistently outside the normal Autotrim range, so no mystery. Then, as the a/c climbs to its apogee, and g re enters the range in which Autotrim is ACTIVE, the THS migrates at an even rate to its NOSEUP stop. At no time do I see a variable rate from the THS, it lumbers along from 3 degrees to the stop, seemingly independent of a reason to do so in such a manner. This all seems inexplicable to me, what is the relationship between elevator and THS in this trajectory?

That is the best wording I can come up with. I started what seemed like a fruitful exchange with MR. clandestino, but found out my question lacked aerodynamic validity, and seriously challenged basic Physics. That's it, no answer, just slag.

Oh, except for a picture of a fifty year old design, and a rejoinder that Mr. Davies knew more than he.

Fair. I think mine is a valid question, and not a steaming pile, as has been inferred. If a pile, please ignore.
Lyman is offline